If I decide I dont want to deal with his addiction (because it's a disease) I am breaking the part where I vowed to support him in sickness
Sometimes the only way thru to an addict is by completely abandoning them to the consequences of their choices. I say this as somebody who has far to much experience with drug/alcohol addicts. It is far less loving for you to enable their poor decisions.
As others have said, he is trying to manipulate you. Protect you & your kiddos. Hopefully that will be the impetus for your WH to get his shit together.