OT - I'm not sure I'd call Nm passive. She's been dealing with a seriously confusing/confused guy who's either drug-addicted or mentally ill or both. By moving out she is taking control of her life.
NM - so, if the child support will cover rent and childcare (you must live in a rEALLY cheap area!) does that mean you can get a job and pay for the rest? Do you have a line on any jobs? What did you do before?
I know this all feels overwhelming, but you can do it - and won't you feel SO MUCH BETTER once you are standing on your own two feet and not dependent on this unstable man???
Sure, he misses you and regrets you leaving - again. This time you need to stick to your guns. What EXACTLY would he need to do for you to EVER consider living with him again? Figure that out and you won't be in danger of falling for his old tricks.
I figure he'd need to: - cut all contacts with oW, including publicly telling her it's over in your presence. - go to IC and drug rehab AND a psychiatrist - court you with regular dates and completely transparent behavior re: phones, computer etc. for at least a YEAR before you would even consider moving back.
etc. etc. Not impossible but pretty unlikely given his past behaviors. Drug rehab and psychiatrist would be the key, I think.