STBXH and I split over a year ago. Things have moved on, divorce going through and I am in a much better place altogether.
H's family haven't contacted me or DC for approx 8 months after a couple of very uncomfortable conversations with MIL and SIL. I told SIL to Fuck Off and I was not repentant.
So, today I receive a call from MIL:
Me: Hello
MIL: I want the fish knives back. You must return them, they are mine.
Me: Erm
MIL: I am in and I want them. I want them today.
Me: I'm out today but you could call next week? Or H could pick them up when he next has DCs?
MIL: I want them today! You must bring them to my house!
Me: I will not return the fish knives. Goodbye.
I know MIL and she must have been stewing for months before the dramatic fish knives call. This makes me smile.
So, AIBU to say "I will not return the fish knives".