(((KJ))) - I think if anyone's being unreasonable, it's your mom. If she wants him in HER house, then fine. As far as who is in anyone ELSE'S house, that's THEIR decision.
You are setting a boundary and your mom doesn't like it. It's sad that she may choose to miss out on family functions, if he's not invited, but that is her choice.
The longer I'm in recovery, the less I want to be around toxic people...even if they're related to me.
I think you're making a wise decision.
Hugs and prayers!
Amy