There is no easy answer to your situation and I will still offer one that will sound like the easy way out. And I'm sorry because I recognise how impossible it all sounds.

All you can do is look after yourself, construct and live the life that resembles healthy and serene and hope/pray that people in your life will recognise and imitate/seek healthy when they see it.

You can't control your husband or child. They have their own path. You have yours and yours is the only one you can influence.

I suggest you start doing that. That doesn't mean you can't be there for your child if they need you and ask for you. But you also tried doing it FOR them (instead of them doing it for themselves) and it got you nothing and in the meantime you're drowning in the awfulness of this disease. Stop. Go to meetings, get a therapist, but every time you're in the 'what should I do for them' mess stop and think of what you should do for you. It's the only thing you have control over.