What is the socially acceptable response to my (34f) exhusband (34m) getting married?

So as the title says, my (34F) ex husband (34M) (together 10 years, separated 3) is getting married in the next week.

We are not amicable. I left, he was abusive, police were involved ect ect.

We are only still in contact because we share custody of two children. This is also deeply high conflict and we are currently in the middle of family court.

I genuinely have no issues with his fiancé, she seems fine if a little naive. I have moved away and re-partnered and am genuinely happy he is getting married - maybe he will finally focus his attention elsewhere and leave me alone.

But, I will be seeing him the day after the wedding to do handover and I’m not sure what the etiquette is.

If I say nothing I’ll be painted as bitter If I say congratulations I’ll be painted as passive aggressive.

I’m not sure what other options there might be 😅

Reddit what is the socially acceptable choice in this situation.