Lexie makes a good point. Talk with your boyfriend and go to the landlord. None of my business but are you and your roommate the lease holders? Is your boyfriend even on the lease?
Are these people planning to leave when the lease is up? Or can you and your boyfriend move?
This all sounds like a disaster waiting to happen. Three years sober is a milestone. Your boyfriend deserves a medal. He's demonstrated courage and hard work. Geeze, gal throw that bum out.
If you are a "normie" like me then you have no real understanding what your BF's been through to stay sober for three years. I certainly don't claim to know from the inside. But all the reading and studying I've done over the last year has led me to understand that recovery for an alcoholic is harder than anything I've ever had to do in my life.
You may have to decide here who is more important to you--your boyfriend or your roommate who has disrespected you and your BF by bringing a drunk into your home.
I apologize if I've been rude or too blunt but I'd do just about anything to help my AH if he could take that leap to get sober.