Think.
Seriously.
If she did come back, would you even be able to bear it? Would you want to go through all this drama for the rest of your life? What is love without trust? How could you ever trust her again? Sounds like she is addicted to sex/drama, and you are addicted to *her*.
Look inside, and figure out why you would even let someone treat you like this. You sound like a very loving, attentive, kind, compassionate and perserverant individual. Spend those wonderful qualities on someone that deserves them, and returns them to you!
It'll hurt for awhile. Believe me, it will. I suggest you contact a counselor to help you through the grief process, and read up on the Internet about the grief process, and accompanyng stages. This will better help you put your emotions in context and process them in a healthy way!
Remember: it will get better and in another year or so, it will all seem like a bad dream! Use that wonderful quality of endurance, and look for tomorrow's rainbows! Healing takes time, and you WILL heal!
Wishing you the best!
CG