Best friend has a partner I can't stick.
We were there at the weekend and he got very drunk (not unusual) and was obnoxious and aggressive at dinner.
Later on, after everyone had retired to bed, I was on my way to the bathroom and heard her whimpering from their bedroom and saying "ow, ow." Shortly afterwards, dh went to the bathroom and there was a nasty row going on, with my friend very distressed and crying and partner being very verbally aggressive and calling her a liar and "I'm glad it hurt."
What on earth do I do? She's confided in me before now about the relationship, but this is worse than I thought. Could I be jumping to conclusions? She knows I'm "there for her," but I can't sleep for worry about this latest development.