TX, I did what I could to crush it and also take the excitement out of it. Many people knew, I was open about it, but also too forgiving.
Strangely, your post only now appeared and shows as the latest one in the thread...
Yes, this is a more extreme repeat of our story. When I met H, we were first long-distance friends (e-mail), and he said he was already separated because his W had an A and mental problems, but still shared the house due to finances and kids. We eventually became more than friends but only saw each other a few times because of the distance. Then I started getting concerned about the lack of movement towards a D and that he was lying, so I ended it. After several months of NC, I talked to him and he had moved out right after I broke it off. It became a long-distance R again and we decided that I would move to the US. I refused to come until his D was final (12 months from S).
I realize now that he was probably lying about many things (although stepkids have confirmed that M was high conflict and Ex was abusive, that Ex dated alleged A partner after the split - he left his wife for her and then she dumped him - and that they were relieved when their parents decided to split) and I was naive. It was my first M and I wish I could turn back time and let the older, wiser me guide me.
H lied to me repeatedly through the years about the A being over.
If he was willing to start something with you while he was still married that should have been a huge red flag to you as to his character. What he has been doing to you is just him being himself. He's done it before, he'll do it again. If you want to be healthy I recommend you get as far away from him as you can. Cheating and lying is a big part of who he is.