should i get back with my "baby daddy"

i was with him for 13 years and we have 2 kids....he cheated numerous times over the years, but what took the cake is he had a long relationship with one of our mutual friends who use to babysit for us, left me and the kids and moved in with her. i was so distraught that i moved me and the kids to a different state. since then him and i have had a good friendship and he has seemed to change. should i let him move back in with us or forget about it