Help getting over a long relationship

Hey everyone, I have been with my husband for 13yrs and married for 5 and a half years. My husband has cheated on me about 6 times since we have been together (I know I should have left but I loved him way too much) anyway we also have 2 children together, and recently he got sentenced to do 4 and a half months in prison. Before going to prison we broke up 2 weeks before because we where just arguing all the time, he moved out. And when he went to prison we got back together for about 3 weeks and then broke up AGAIN ARRR lol..but I would and still visit him as friends for the kids sake as well and then one weekend I got told I couldnt see him one visit day (by him) because he had to work on the farm out there, but turns out he had a girl visiting him.. they worked together before going to prison.. anyway I was sooooo angry that he would do that, anyway I got over that and we continue as friends, but she is visiting him more often and I think they are getting close. I guess my question is how do you move on from someone who you have been with since you where a kid??? Any advice??