Should I stay or move on?

[Renee]

My bf and I have been together for 3 going on 4 years and we have a baby together. When I was 2 months pregnant he went to jail and was gone until i was 7 months pregnant. I did everything for him when he was in jail. i wrote letters accepted phone calls and went to visit him a few times. I stayed 100% faithful to him and made up in my mind that i only wanted him. Anyways everything was good when he came home but after a few months he started hanging out with his friends a lot. Sometimes he would hang out at night and wouldnt answer his phone. One of his friends made him a facebook page and i found his password and saw that he messaged 2 females. I cried in front of him and l let him know how bad that hurt me and he said he would delete his page. i found out a few months later that he had made a different page under a different name. i demanded he give me the password and i saw him trying to talk to 10 more females. i also found out he had a match.com page. he cried and asked me not to leave him and me being stupid i agreed to stay. he acts a lot better now and doesnt hang out as much and treats me and our child good but i just cant get over what he did. one minute everything will be good then the next minute im bringing up what he did. I think im mostly hurt because none of the girls looked like me. I am 21 and he is 26 and i feel like he might want someone older and more slutty than i am. he is a great father. what should i do? should i forgive and forget or move on? I cheated on him before but it was the first year of our relationship. please help