I tried similar with my alcoholic ex, it didn't work out. He would visit, disappear to "the shop" for an hour, and come back drunk, I'd tell him to fuck off, then make some excuse to ds for why he had to go home early.
We'd go to stay with him and he'd be in bed in a drunken stupor when we got up the next morning, and I'd have to make excuses again.
The arguments were just the same ones as when he lived here, just every other day instead of every day. He eventually ended up going on a bender, and harassing us terribly for a walk or so, before the police finally got a hold of him.
I wish I'd never started any of it, and had told him then to either find a sensible relative to supervise contact, or sort something out via social services. Even when he was on his best behaviour, having him in my home, being disney dad (he'd show up with a stack of presents, takeaways etc but wasn't paying me maintenence, so I bought all ds's clothes and shoes etc myself), and after all the shit he'd put me through, was hard to stick.
I think you're very wise to put your foot down now. E-mail him (polite but firm), and see if/how he reacts?