What’s the worst thing someone connected to you did?

Here's one for you. Sister in law claimed she was divorcing her piece of work abusive husband.
Mother in law takes a little chunk of her retirement money and bought SIL and my nephews a small townhouse so they would have somewhere to go and live.

Well 3-4 months afterward piece of work husband moves back into the free townhouse, mother-in-law says "no I didn't buy that for you I bought it for my single mom daughter". But they won't leave. House was titled to MIL and SIL jointly.

Cue about 4 years of legal wrangling to get them out, during the course of which SIL attacked my wife at a birthday party for my nephews and tore her ACL.

Fun stuff.

FWIW, piece of work husband ended up moving out, running off with another woman to like Arkansas or some crap, trying to have a kid with her, hasn't paid a dime of child support in years. A real treasure.