Suspected sexua| Misconduct

I was in a sexually uncomfortable relationship with my ex husband before we divorced, where he liked to fondle me and also initiate intercourse with me while I was sleeping. We have been divorced for several years regarding this issue and now he has access to my child and I am getting concerned. For example, my son asked me why I didn't check his penis to make sure it was clean. Additionally, my son has become very withdrawn from my fiance, whereas before their relationship was otherwise comfortable.

What should I do?