How do I break this cycle?

Some of you might remember me from the beginning of the year. I read every day and debate if to post.
Brief synopsis: I found out Jan 2nd DH had bee having an affair for 2 months and she was pregnant ( I'm 54 and have had 4 losses and two children with ex). Two weeks later a 2nd woman messages me climing to be his gf of 3 months. He moved out. First woman had an abortion but they still talk claiming it's work, and I know he's probably seeing the 2nd.
He's an alcoholic and had been sober 8 years until November last year. He now drinks again.
At his persistent we began talking end of February. In April I agreed to see him - like dating - twice a week providing he was not with anyone else.
Well..... he lives at home. His parents severed all contact with me despite the fact we were very close. DH texts sporadically, ignores my calls and still lies, disappears for nights, claiming he's sleeping or not well. He's cancelled 2 weekend dates claiming illnesses and then off radar.
I'm miserable - I know the situation must end, but how do I sever contact? I find it impossible as just worn down.
When we are together it's as if we've never been apart. And we actually get on really well.
I just don't know how to break this cycle. Or begin a life without him.