Phoebe, change is difficult. Especially after 19 years. But it sounds like the last 19 years have been really difficult too. The good news is you get to choose what the next 19 years looks like for you. It's completely up to you. You can't change him. You can't fix him. But you can fix you. You can work on you. You can protect your children from crack addiction.
Future tripping and worrying about stuff that hasn't happened yet or things we can't control can destroy us. And repeating the Serenity Prayer over and over and over again can provide serenity. (I know I'm just repeating what others have said, but those posts above mine are very wise and bear repeating.)
Staying in the present and focusing on the the small things that we can do to improve our lives is so productive. And for me anyway, being productive makes me feel better. Baby steps help. Lists help. Goals help. Boundaries help. Meetings help. Counseling helps. Coming here helps.
Hang in there. I know it is scary but things will get better FOR YOU. There is a saying in recovery circles - "don't quit before the miracle."
Not his miracle - Your own miracle.