Well Lilac ! You said he'd come up with something, I'd say he's excelled himself
So, battleplan.
He'd "rather" they were with him that week. Well, you'd "rather" he wasn't an inconsiderate WN. Your answer to that - nothing. Because his reasons are beyond childish. So, don't even acknowledge or address them. If you do reply, I would just say "I received your reply, so that week the dc will be with me. What days did you want to have them on our return/before we go?"
As for the dc's potential questions about safety etc if/when he starts to work on them. Obviously you know them best, but could you just laugh it off, kind of Silly old dad, he's such a worrier, look at all your friends who went abroad last year, they're all fine. I know it'll be hard, but it's you they trust and respect, so if you're not concerned then hopefully they won't be.
It's always hard suggesting what somebody else could say or do, because each situation is so unique and has it's own little quirks. For me personally, I had to accept that if I took this approach it would be the end to any hope of co-parenting. That I would most likely never have a reasonable relationship with my dc's father. But for me, this is the lesser of two evils. We on this thread could all turn into Mary effing Poppins, it wouldn't make a scrap of difference. They won't co-parent, fine, neither will we.
SanFran really glad you got out to visit your mum and dad, and that it's been comforting.
Homely As Nats said, maybe you could call his bluff and say he's not having o/n for x, y, z reasons. When he threatens court, say fine, see you there. D'you think he'd actually do it?
In answer to your questions, they had o/n from the outset. 2 evenings a week at the moment (one is o/n) and one weekend day. They often see him more though, perhaps an extra evening or o/n. Also more during the holidays. They would have been 8 and 10 when this started.
FeeltheNoise That's just awful that you've had to go into emergency housing. I agree with all the previous posters. You can't do anymore than provide supervised access to a drunk dad, and you certainly shouldn't have to. Maybe you should look into a contact centre. As a pp said, if he turned up drunk he would be refused access and that would all be recorded. I know it's all money and time, but could you get a simple letter sent from a solicitor to him. You could outline why you'll no longer supervise access, that he has to arrange a contact centre if he wants to, and that he is not to contact you again. Also, that you have reported his actions to the police, and will continue to do so. Then block him from your email/phone etc. Say he can send any info re the contact centre via your solicitor.