Holy crap

So I need some advise or just really someone to talk about this with. I feel like I have know one to vent to.

So back story... I was married for 12 years broke up 4 years ago. Had another relationship for about 3 years and have been now single since June. My ex husband has a best friend. Hes married, his wife is in prison. This guy has also slept with my best friend. Well my ex husband is now in prison and will be gone for a very long time. My ex husbands best friend had invited my kids to spend the night with his kids like he often does. I've known this man for 15+ years. Well this past weekend when I went to drop them off he asked if I'd like to stay for dinner. I said sure we eat and had drinks while the kids played. Bed time came and I stayed and drank and talked. This man has never once showed in any way that he had any attraction towards me, so when we were talking I was legitimately talking to him like I would a girlfriend. He talked about missing sex and eating pussy. And I agree how I missed being with my recent ex.but I also had talked about how it's hard for me to find another guy because I dont have sex with out there being love involved. Out of now where he came behind me kissing on my neck and started rubbing on me. I instantly said woah we cant do this and he just kept at it. Some how got me to his bed got my shirt off. I was trying to get him to stop with out being rude cause I started to feel like I provoked him to feeling that way. He was pulling my hair, grabbing my throat, biting and kissing my neck and down my spine. It felt amazing but I felt it was wrong. I asked him to calm down and just cuddle me for a minute... he fell asleep and i snuck out. Now things are very awkward. I dont know if I should say something to my ex or my best friend.

** he is still married to his wife, she is ok with him having sex while she away. At least that's what he had said.