Cheating

So me and my boyfriend have been together for a while now and we have a 8 month old baby. During our relationship he has done some foul things to me, cheated on me, lied to me and a number of other things, we agued pretty much everyday, so we took a break,- 6 month break and now we finally have came back together and we our trying to make it work, because for one we love eachother and for two for our baby boy. But, the cheating he has done in the past I really am having a hard time getting past? What can I do to help us move pasted this? Like we are good so far but that past cheating consumes my mind all the time. How can I move past this?