Why cant I stop hurting over this messed up love?

Me and this guy were in love.We dated for 10 months and once when we broke up he slept with another girl because he was drunk and probably hurting over it.I found out 5 months later.He lied through our whole relationship since he didn't want to loose me.Every once in a while he would cry and say he knows I'm going to leave him.He felt very guilty but I cant forgive the fact that he slept with somebody else.I don't know if he loves me.I love him more then anything.We've been broken up for a month now.I found out i'm pregnant with his baby.I met and talked with him so that we could decide I needed an abortion.But now all that meeting did was open us up to all this pain again.Now we have to start all over getting over each other.It hurts so bad.I don't think I can ever forgive him.But I also know that I cant be without him.Should I give him another chance after another month or two?He doesn't deserve it.I can tell you that.But this is the hardest thing ive ever had to go through.