RB, I think the only thing I would add to what you're planning now is to get the kids on-side. That doesn't mean they have to take sides, but that you spell out your intentions and tell them the reasons for doing it. So they understand and don't inadvertently encourage him to cross boundaries.
They may push back, but it shouldn't be a discussion of right or wrong, just putting them in the picture.
In regards to your plans for getting out of debt, I think it would be a very good precaution to seek legal advice, even if it's just a free clinic or legal aid. In a marriage it may not be relevant whose name a debt is in. At least find that out, because voluntarily paying off loans just because they're in your name may still leave you liable for credit card debt in his name. Very important.