Is it normal i'm making my girlfriend choose, friends or me

My girlfriend and I have been together since high school. We were best friends, totally platonic for over a year and then we started dating when we realised we wanted to spend the rest of our lives together and we felt safe around each other. After High school we moved two Provinces (in America you guys would say States) away because of University, everything was still fine but in our final year she suddenly changed on me and it felt like I didn't know who I was talking to we fought alot and finally she broke up with me, I was so devasted I kept on trying to reach out but she was so mean.. it's like she became someone totally different. She would post stuff on Facebook subliminally pointed at me just for the sake of hurting me and after 3 months of trying to reach out.. I gave up. A month or two of giving up she sent me a long email crying and saying she was going through things etc and she's sorry. One time she gave me her memory card cause mine was full and I saw a different picture to her(she thought she had deleted everything but certain things were still there in files). Her friends talked shit about me, she flirted with guys through out our relationship (since high school). She slept with her ex's (while we weren't together, to be fair and she has never cheated on me if you don't take flirting as cheating) and when I confronted her she cried and said her friends influenceD her, she regrets everything and the way she treated me, she wishes she could go back to the past anD erase everything. So I tried playing it nice so I don't look like a maniac but recently I've lost it when I found out she slept with her ex's and her friend was basically the mediator.. now I'm making her choose between cutting off all her friends or me, she will have 0 friends if she does it and her frienD is her best friend since high school grade 9, one she met in University and she has graduated this year (to help you understand how long and serious these friendships are). I feel really bad for doing it at the same time I love her and genuinely want to give her a chance but I feel she needs to sacrifice something big to show me she is serious and her friends are a bad influence anyway. They've always talked crap about me but when I'm around they all smiling etc. And the last time I tried breaking up with her she drank pills and landed up in hospital. Everytime I mention leaving she says she'll end her life and I believe her. My point is..is it normal that I've reached a point where I am making her choose between me and her friends.