Am I at fault for refusing to give my mum back her MacBook she bought and giving it to my (divorced) dad instead?

In the most simplest brief: in 2017, my dad (who pays for mostly everything of mine) bought me a 13” Pro. Fast forward to 2019, mum buys a 16” $4000 Pro (all upgraded w/ Touch Bar) and realises she doesn’t use it much and gives it to me.

Mum calls dad to confirm, and dad wants the 13” for himself to which mum gives an ultimatum:

1. pay her for the laptop (that he already bought?) or

2: she keeps it, as she thinks it’s unfair considering the price she paid.

He does 2 and she keeps it. Mum gives the 13” to 13/14 year old me to put it in factory settings, which isn’t easy – and I break it. Won’t turn on, and she’s okay with it as she’d prefer a desktop. I sell it for $800 and I give her $100 towards the desktop.

She buys a Dell. I keep this a secret from him, as he’d be furious. Now in 2022, dad buys me the M2 air in exchange for the 16” as he believes she still has the 13”.

I can’t say no to a new MacBook (like seriously?) and accept the offer. I tell mum and she’s livid, she is demanding the 16” and finds it unfair. Now 17 year old me, is in the middle. Dad still doesn’t know, and I don’t want to tell him.

She wants the laptop back, and I say I think he should keep it. Now she’s rearranging the story of 2019 to make herself look better, and I am about to be thrown under the bus. I do not want him knowing!. He bought me a 153k brand new car, dentist aps, 5k dog, clothes, electronics etc etc.

She on the other hand, nothing. She’ll spend 2k on botox and filler and not on anyone else (and then complain about money issues).

So, wth… I can see why I would be considered a bad person for favouring my dad or for refusing to give her back an item she paidfor, but considering her personality aligned with her actions of the previous laptop (wanting my dad to essentially repay the 13”) I think I am justified in letting him keep it, but not lying.