Ok...... this is completely horrible advice. lol
I can't give a perfect answer and there are probably a ton of things I am skipping over and not taking into consideration, since I don't know your full situation... but here's a woman's perspective on it.
I know long term relationships can be very hard and frustrating to get over once you're at that point, and you may not ever stop thinking about her, but just accept it. She was an important part of your life even if she did screw it up. However,
keep yourself busy and refrain from trying to contact her. She won't talk to you until SHE wants to anyway. She seems like a very selfish person and has no respect for you right now. It really really sucks that you didn't get any closure on it.. but somehow you have to figure out how to work with what you've got and get over it. It may be a bad comparison, but it's reminding me of when someone close to you, whom you thought was a happy person, suddenly commits suicide. You are left standing completely dumbfounded and heartbroken and can't even comprehend how to deal with the situation.
A big part of it is time. You MUST be patient with yourself. But DO NOT rush into any relationships, and do not just have mindless sex. Bringing more people's feelings into the picture will only complicate things further.
I know it's hard, but believe me when I say that that will probably never happen to you again... it isn't a very common situation (if you pick the right person to be with, someone that actually really cares about you.). And there are good females out there.
And when all else fails, there's absolutely nothing wrong with being single! :rofl:
Just my :2 cents:.
Good luck!:wave2: