About all I can add is that your parents are enabling his addiction and until he hits rock bottom and decides it's time to truly sober up, he will continue on as he is, and until your parents kick him out and/or have him arrested, he won't hit rock bottom.

Good luck wyndhy, I'm sorry to hear you are going through this. ((Hugs))

__________________
Put me on wheels and I'll turn tricks.

Clever? Nah, I ran out of that years ago. But if you find this, let me know, k?
"The road goes ever on..." ~ Tolkien

In memory of my friend skip...
Go then, there are other worlds than these