Dealing with people you don't like at Christmas Part 2

[MonkeyTennis34]

I posted on here about a month ago about my SIL's abusive BF.

After a lot of discussion, me and DH are going to invite him for the family get together on Boxing Day.
We don't want to isolate SIL.

I'm posting today to ask for advice on how to act around him.
I know I need to be polite!

For context, SIL told us at Easter that he has been verbally abusing her for 2 years, threw a hard object at and that she had to leave her house once as she felt unsafe.

They split for a while after this disclosure but then she took him back.

We haven't seen him since February.

Bump

We have something similar. It's tough but we've found that the bigger the crowd the easier it is to briefly make polite small talk then go get a drink and forget to return. We go easy on the drink while that ducker is there and bitch and rant about them after they leave.
Nor much else you can do.

Thanks @PabloTheGreat
I think you're right...