I feel bad though because in the end I raged at her words and she suddenly became calm and happy to see me hurting inside.
Bkkabri, does this sentence make any sense to you? Why are you feeling bad? First of all, you were only with this woman two years, you don't have any children, you weren't married, doesn't sound like there was a whole lot there to begin with. Secondly, why are you feeling like a schmuck because she was a bitch? You couldn't have done anything different or better to improve the situation with her, that's why these people are such head cases to deal with. It wouldn't have been your responsibility to do so if you could.
This is going to sound really crude, but I don't know how else to put it: Find your cojones, put them back on, and go on and start living your life in the present, not the past. You already admitted it was a nightmare. Time to wake up and move past this.