Madly in love with my ex. How do I get her back?

I'm 22 and had been with my ex girlfriend since 14 up until last year. She was my world, I treated like a princess and things were great up until I screwed up. My parents never liked her and thought that too much of my life revolved around her. I'd never even listened to them about her until we had this really stupid fight. Their words really started sinking in and for a second there I thought they were right and I broke up with her like a fool. Biggest mistake of my life. I didn't talk to her for like a week when I finally realized what a mistake I made. I called her but she some how found out that we broke up because of my parents and she said she never wanted to see me again. We argued and then we basically stopped talking, for like 4 months. We'd never stopped talking more than a couple of days. I'd heard that she was with someone else but at the time, I didn't care. I missed her so much and she was ignoring my calls and texts and just went to her. I told her how much I loved her, wrote her a poem, the whole nine and she said that we couldn't be together. I didn't understand. I begged her to talk to me but she wouldn't. I heard around that she was pregnant by another guy. I was so pissed off. I mean, I'd never been that angry before. I confronted her best friend and she said it was true. At this point, she was about 5 months pregnant. I asked her if their was any chance the baby was mine and she said no, but I didn't believe her because we had broke up about 5.5 months before that. I kept asking her if the baby was mine and she told me to leave her alone and then I told her that I'll take her to court because she wasn't telling me anything and she told me that she slept with a childhood friend 3 weeks after we broke up. I was so depressed. She's the love of my life and she was having another guy's baby. I can't describe how painful that is. I asked her if she wanted to be with him and she said she didn't know. She had the baby 2 months ago. They're not together, but he is around for the baby. I told her I still loved her and she said I hurt her. I know some of you are going to say I'm stupid and just find another woman, but I don't want anybody but her. I don't care that she has a child with someone else. I'm willing to accept the baby and this other guy. I just want to be with her again. I know the guy wants to be with her, but I'm pretty sure she doesn't want to be him. I love her so much. How do I get her back?