I have a damaged dude

Amber
So my SO and I have been talking long distance for the past 4-5 months. I'm moving to him in June. 
He has been cheating on and treated horribly by both of his ex wives. We are like two peas in a pod.. but he is so extremely afraid of being hurt again as well as not believing that he is my one & only. The distance is taking its toll..
I do my best to reassure him but he tends to go into a shell when he gets these feelings of inadequacy.. 
Has anyone ever dealt with this before? I just want him to know I'm not his exes.. but it's hard to get the point across..