Im 20 and have been with my boyfriend on and off for about 6 years. He has gotten me pregnant twice and I lost the first one from stress. I decided I was going to definitely keep the second one and do whatever I can to stay healthy. But my pregnancy went from good to horrible when I couldn't keep any food down. Ive been in the hospital countless times and my mom kicked my boyfriend out of the house. He is now 8 hours away and I recently found out he was cheating on me when he went home for a couple months. My mom hated the fact I was going to keep the baby and throw my future away. All my friends were disappointed I let myself get pregnant and they all eventually persuaded me to get an abortion without my boyfriend being there. I felt weak and indicisive. Once I found out he was cheatin I made the appointment without thinking about it. I got the abortion about 5 days ago and it was the worst mistake of my life. I hate myself and I'm so insecure now. The girl he cheated on me with was skinnier than me and I'm a fat cow that got fat from my first pregnancy and even fatter in my second one. (My pregnancys were about a year apart) I hate myself I see a fat murderer when I look in the mirror. I decided to stop eating until I can learn to love myself. Im also kind of going crazy. I feel like the devils in my room so I sleep with my light on. Someone help me?

What you need is to see a professional. With counseling and the right medications they can get this back under control.

You don't sound weak to me. You do sound indecisive, which 99% of us are at 20. You were getting it from all sides. You are only going crazy if you let the whole world tell you how to feel. You can feel all the guilt you want, but guilt is a self-indulgence, a self-pity in a way. You can't undo what is done. You can get pregnant someday by plan, not by accident. Want to do something? Volunteer at a hospital holding preemies or something. It doesn't even have to be related to babies.
The boyfriend was bad enough living at your mother's, and then on from there. Who needs a guy like that?
Get therapy, join a group. Groups are often more helpful because you meet others with at least as many problems as you, and you all help each other.
Don't wallow in guilt. If you are against abortion, just realize it's now a part of who you are, and you use it and learn from it and it makes you a better person.