My nephew got married a couple of years ago, in a very rural location. DH and I were sharing accommodation (a holiday bungalow) with my sister and her DH, we live quite far apart and don't see each other often so that was nice... till my sister went to bed and BIL turned into an absolute drunken wanker. I have never see him like that before, and would prefer not to see him like that again. He's such an amenable chap when he's sober, a million and one red flags flying that night. My DSis seems completely unaware. 
So, next year, Covid permitting, my niece is getting married in the same location. And DSis has suggested we share the same accommodation. I need an excuse not to, BIL completely ruined the day for me and I actually had several sleepless nights over his behaviour and the ramifications thereof. I almost posted a thread, my head was so fucked.
DH has offered to "make sure" he can't get the day off (he works shifts and often weekends, the wedding date is during school holidays so maybe parents of young children have booked all the time off already... ) but I'd quite like to attend the wedding, just not share accommodation. Any ideas?