Wow. A lot to unpack. The adult woman living with three 15-year-olds caught my eye. Maybe she imagines herself a Wendy to their Peter Pans. She may still feel that role will suit her with your ex-associate. ('friend' would not be how I characterize him)
Agree with the rest, he's a user. As far as his support and stuff, he's got the other men in the sober living house, yes? And support from other addicts may be useful. I'm on the fence as to how useful. I guess there's the element of 'been there, done that.' If one wanted to stay faithful to one's partner, do you get advice from someone who cheated, or someone who hasn't? Maybe both.
As for no contact, meh, maybe he's got it in his head that he doesn't want to add the task of re-establishing a relationship with you added to his to-do list. Maybe he's ashamed and wants to leave the past behind. I had a bf that treated me poorly. Come to find out decades later, he also did the same to his male buddies. He did actually move a thousand miles away to reboot his life. To read his obituary, it didn't sound terribly fulfilling, but it was his life to live.
As someone who invested 25 years with an alcoholic who wasn't anywhere NEAR this dysfunctional, I would say the band-aid's been ripped off, leave the wound in the air to heal, and move on. It's mighty uncomfortable at first, but a lot of things heal more quickly in sunlight and fresh air.