Are you documenting? The more you track, the more evidence you have, the more you will have on your side. It sounds like your friend went through this decades ago. Things have changed a lot.
My uncle recently got his kids from his wife in a similar situation. Don't you owe it to them to try? What's better... leaving them to rot in this situation, and let your wife take you AND them with her, or fight for them, and show them that it's NOT okay.
Addiction is a communicable disease. What do you think is going to happen when you teach your children that it's okay to put up with it?
1) They will catch it themselves, and become addicts.
OR
2) They will learn that this is what relationships are, and seek out similar relationships.
There's a chance they won't, but I'm dealing with the second-generation aftermath of a parent who didn't think it was worth the fight. And now I have to fight for MY kids. I refuse to continue the cycle.