Okay.. that sounds a lot more serious then. That kind of thing you don't have to put up with. I see it as two choices.
You tell him what's bothering you and keep trying to help the kid see right and straighten up. The chances aren't that good but you never know. In the end of it all you don't want someone who is going down willingly take you down with him.
The other thing is you tell him you don't want to be friends anymore and tell him why and see how it all plays out.
You might want to let your buddies in on this too. Especially if there's someone at the firehouse who is sort of a mentor type. Sometimes our friends can help us see things we don't see.
Wish I could help more but that's about the way I see it.