Is kissing cheating? Can you help?

Can someone help me?I had met my current partner back in 2006. We had the best relationship ever. At the beginning of 2008 he asked to move our relationship on by starting a family and moving in together. I fell pregnant in Feb 2008.Over that time he became increasingly less interested in me as I got bigger, but I also I felt that he just didn't want to be with me. I remember going to work everyday and crying because I was so worried about my future.Eventually I sold my funky apartment and we bought a new house together. For some reason though, he was still real cold towards me. Just after giving birth, I felt so horrible and disgusting just with how my body was, then to make it worse, he was really distant with me.I found out about 6 weeks after birth that the whole time I was pregnant, he was sending very sexual texts to an old "hook up". Also I found out that when I was 34 weeks pregnant, he went out on the town and kissed another girl - I think that he even wanted to go home with her but didn't. He also left his facebook page open one day and I saw all these emails with other girls where theres constant flirting etc.Since this has all come to ahead (just a few weeks ago) he has sincerely apologised and said that he was so scared about becoming a Dad and committed partner. He really wants to make it work and become a happy complete family. He said he has realised how hurt I am and that his behaviour is totally unacceptable. He said that he really wants to be a good partner and father to our baby.Although I would like to believe him, a big part of me can't get past all the hurt I have felt and not sure if he can remain completely faithful - ie no more flirting. I have never felt so empty and hurt as I do now. The pain hurts so much that I can't put it into words. I have been through SO MUCH and gave so much of myself to carry his child - I've really hit a bump here - one part of me would love to believe him and move on, the other side of me says that I deserve so much more and to have self respect - If I am understanding everyones view here... "once a cheater, always a cheater?"HELP ME PLEASE??? I would appreciate peoples thoughts -