In the first third of your post, you write that you cannot and do not trust AW with DS4 - that immediately disqualifies Option #3B in my mind. And I think everything should build off of there.
Getting a gov't job with benefits and the retirement options they have surely must be a good deal, especially since you are paying COBRA. COBRA at my company, even on HSA, is around $1400/month for me, AW, and one kid. That difference alone should cover childcare. Now, can I ask how much of a salary hit you would take? Long-term, having a gov't job almost always pays for itself in terms of benefits and pension. You also have to think long-term.
You don't HAVE to sell right now, do you? I understand that you are trying to save $$, but that would be just another disruption to DS, and if AW is not working, she is going to want living expenses, and if you just leave her in the lurch, she will probably get a lawyer and sue you for living expenses - which then adds additional things to your burden.
IMHO, and I'm not you as a parent or spouse: get DS ASAP from her family in State C and get him back home BEFORE she gets out of rehab. Step 2 - get him in daycare ASAP and get him established there, and get him him into a safe routine. Step 3 - accept the new job unless it's a horrendous hit to your bottom line - remember, you are traveling far-and-wide for clients, will this new gig afford you to be home, and/or closer to home more often? That will save you money and stress.
Bottom line - look at the total overall costs associated with this job. But first and foremost, get DS back, get him in daycare, and make sure he doesn't spend ONE SECOND of time alone with DS. Oh, and get moving with an atty. who can help you with all of this.
We're rooting for you and DS