@Cantstoptheshitshow
You've nothing to feel guilty about here. It's really important that you start putting really strong boundaries into place to protect yourself. My bestie is now okay the other side and 5 months sober. Boundaries I had:
Do not call me when drunk. I'll end the conversation.
Do not come to visit if you're drunk. I will send you straight back home.
Only you can make changes, I'm not here to fix you.
I'm your mate, not your therapist.
The final one was that if boundaries are overstepped, I WILL walk away. I made this one very, very clear. Be prepared to do this too, as you have to protect yourself against being dragged down with them.
My mate is under no illusions that is they start to drink again, even just one, I'm gone. I'm not prepared to watch them kill themselves slowly.