Quick back story - we split up 3.5 years ago, very acrimoniously at first. His behaviour over that period was pretty emotionally volatile but we’ve managed to get past it and now get on well, attending school stuff together, he drops by to see the kids for tea sometimes and, specifically, we all spend Christmas Day together (with my family - his is another story!). He is completely happy with the Christmas arrangements and has never wanted the children to stay at his for Christmas, he’s rather they stayed at home and he came to see them.
This year his girlfriend is away and so he is alone on Christmas Eve and so he and my DS (who is almost 9) have asked if he can stay over tonight so he can be there when the kids wake up tomorrow (we also have a DD who is 11).
What do I do?
I don’t want him to stay - it’s my home, I want to relax after the kids have gone to bed and not be sat watching TV with my ex in some bizarre flash back to Christmas past. Plus, he can always always turn a situation to being about him and I am very anxious that at some point he will get maudlin about missing us all and wishing he was still here - he insists he won’t but it always used to be the pattern and I don’t want him staying over to spoil Christmas Day.
On the other hand it might all be ok and my son so wants his dad to stay because he has a vision of his dad being here as soon as he wakes up and us all doing presents together. My DD is less fussed as she clearly remembers that when her dad was here he never used to get up straight away anyway, there was lots of ‘in a minute’ and ‘after my coffee’ 
I’ve currently said no and my ExP says it’s fine if I don’t want to but I feel mean - should I let him stay for one night?