[1/2] I'm no expert (although we could use more info) ...
I'm no expert, so take this with a grain of salt. I've also been married for a long time, so I'm long removed from new relationships and trust that has yet to be established.
Recently, I'd noticed that maybe we were driffting a little bit apart and I wanted to take the time off from the holidays to talk about it, spend some cool quality time together and work it out, because I love her to death and if there had to be changes on anyone's part I wanted to make sure to make those changes because I don't want t lose her.
This is good, it's always good to make time for her. Nothing can go wrong when you do, as long as you don't have expectations on what may come of it.
Well about one week 1/2 ago she went to this school party to celebrate with her classmates. At midnight she called this guy and went to his house. She got home at 5am.
Okay, that was just a bad move on her part, why? Just how it looks. It's not that she was wrong, unethical or anything else, just inconsiderate of how it looks, and how it could make you worry.
I stayed up until 3am waiting for her really nervous and super worried. She doesn't have a cellphone and I didn't have the number to reach her at. I even gave her money so she could grab a cab.
Did you tell her you trusted her before she left? Or in what way did she leave you then? The key is that you can't flop on what you say, you have to stick with the same view before and after. As such, I'm kinda confused here (not enough info), so please explain this part further (again, not enough info).
Anyhow, the next morning she woke me up to tell me. I freaked, I lost it. I felt super betrayed. She said she did not kiss him fuck him or anything like that. They talked about their feelings for each other and how weird that was.
Again, what did you think when she left to talk to that guy in the first place? What did you tell her? Did you trust her? Did you say it was a bad idea? How did you leave it before she left for his house? And what did you say afterwards? And the next day.
Consistency and honesty is what builds relationships, and if you say one thing, then flop to another later, she can't entrust her feelings to you. Now if you told her you didn't want her to go, but let her go telling her it will adversely affect you, now that's another thing. She should have realized it was going to negatively impact you, and there was no way around that if she left.
She said I didn't deserve that and she came back home.
But why did she leave in the first place? Why did she have to be with him to realize that? I'm not saying she's wrong or right, but I'm trying (as you're probably also grasping too), what she was thinking? It's not about what she did, but what she will do in the future in the same situation.
Relationships aren't built on what happened in the past, they are built on what you can entrust the other with the in future. That past defines that, but harping on the past without looking at it from that angle is just hurt, not help.
I spent the holidays completely alone. I was in no mood to go see my family and bring everyone down. I also didn't go to her parents' place eventhough they still invited me and told me to hang in there.
Okay, hold on. If you told her parents, that was your first mistake. You never,
ever include your or her family in your relationship and any troubles. I can tell you the #1 thing that hurts relationships, especially marriages, is taking anything, and I mean anything, outside the family.**
Now if she did it, and not you, then you need to tell her it's best for her to keep things private. It's not merely for your protection, but hers as well, emotionally. The less people know, the less gossip, the less misinformation, the less confusion, the easier it is to work things out.
** NOTE: Now I hope no one else who likes to pick on me tries to say I'm saying you don't share spousal abuse with others and whatnot. That would more argumentative bullshit. That's not what I'm talking about here, I'm talking about general disagreements, attitudes, issues of distrust, etc... that you work out on your own that is not a criminal act. 
Tonight she called me to tell me she missed me a lot and might come back home tomorrow. I asked her if she had thought about the situation and if she would focus on us. All last week I pleaded to her to stay and work things out.
I'm confused, she left? Did she not want to deal with it? Why? Did you accuse her and not believe her? Did you worry about your future and how you could trust her? Did she not given an adequate answer on why she left? Or somehow convince you she wouldn't leave in the future?
Understand your focus should be on why she left in the first place. Is it something you said? She didn't consider? Combination? I know it's hard not to be emotional, but what matters is what she would do in the future, to avoid this issue for both of you?
Again, you're not giving us a lot of key details here to help you.
I could have said fuck you I deserve MUCH better than this but I don't want to push her away. She said she's thinking of moving to her folks' place for a few months to think things through. Folks in your opinion should I go along for this shit ride? I've been there before and in my opinion if she leaves I think it's the beginning of the end. I don't eat or sleep anymore. I'm not productive at work either. So anyhow tonight she said if the problem was just her and I it would be easier to focus, I asked her if he's still on her mind, she said yeah and doesn't understand because she doesn't know him, not physically attracted to him and said she loves me to death. I'm so confused right now.
I think it's important for you two to stay together, period. That means having to deal with each other. And if that means finding you two cannot be civil and without an emotional roller coaster ride, then that's maybe what you need to find out.
Because if you can stay together and be together, it's a good sign you can work anything out. I think you need to shunt both of your parents out of everything. I know it's so easy to go to your parents and ask them for advice, comfort, etc..., but another, #1 related thing to a relationship is that she becomes the to-go person, period. You never use your parents "as a backup" anymore, and that goes for her too. It only adds complexity you don't know, and trust me, I've been far more hurt by consulting my parents on many things than if I would have just talked to my wife, on all sorts of things.
Your parents and her parents don't know the values and trust you and she share. They cannot give you advice that works well, other than the advice that it's for you two to work out, and they should have 0 input. I'm serious. Some parents try to butt into relationships way too much, and offer advice. The only good advice a parent can give is to keep your relationship and its issues to yourself (again, barring criminal issues, of course).
I even said to her, be clear Babe, if you want to pursue thins fling with this guy go for it but you will lose me forever, it's your loss.
No, no, no! Dude, ultimatums never work! That are 100 other, better ways to put it, like ...
- "You should know what you want, what you have and what you would be giving up"
- "I will still be here for you if you come back, but understand it won't be the same anymore, as I'll always question"
- "This isn't about right/wrong, this isn't about fair/unfair, this isn't about him/me, it's about what message you send him, me, etc... with your actions, your indecisiveness, your lack of involving me"
And countless other things. You have to get past the hurt, ultimatums, emotions, and get to the bottom of ...
- Why did she go over there (including what you/she said before and after she did)?
- What she expects you to think afterwards?
- Why it went outside of your relationship (parents, etc... and how you're going to avoid that in the future together)?
- What does she want out of the relationship, it should be fairly clear by now, unless she honestly doesn't know?
In most cases, people know, they just can't be honest, and I think she's not being honest with herself, or she's scared to commit, or she thinks she has to "do something" to confirm. That's when people get stupid. They sleep around like it will tell them whether or not "it feels the same" as with you. I seriously doubt she's done that, but she may be stupidly thinking she may have to do something so radical. I don't know.
But the key is, you gotta get to the bottom of it, and the sooner the better, so she doesn't do something stupid. You have to lead by shedding the emotional trail, being hospitable, being responsible, taking control of the conversation, and finding out just where you and she stand. Don't call it "cheating," call it "inconsideration" and a "serious question to how considerate she will be to you in the future" (when she left, then can't account for anything, much less created doubt that was unnecessary).
