Liz, from my experience, it is better to make the divorce complete and not stay in any kind of financial or legal joint arrangement. What is done in the divorce is legally enforceable, and what is left to do afterwards, has no legal power of enforcement. It leaves you open to re-negotiation, and if he continues downward in his alcoholism, that could be very problematic. I expect that it will be enough to deal with co-parenting.
Hugs,
ShootingStar1