Remind me why I should let this go
Well, how about because just because toxic people happen to be related to you is no reason why you owe them any more consideration you would give a stranger who is toxic. Unfortunately, we cannot choose our family members, but we sure as heck can choose to leave them to their own toxicity and not allow them to treat us like crap.
I am VERY choosy about who I allow to see my facebook page. No one, even family, automatically has access to ways to upset me or mine.