AITAH for backing bags and leaving MILs house with baby

Arrived at MILs house last night (flew ~7000 miles) and less than 15 hours later I packed our bags and left. We woke up this morning to find our 20 month old daughter’s hair cut (first hair cut). I told her how upset I was as that’s a first I can never get back. SO also furious and was shouting - I don’t condone this but I understand. We are now staying at a hotel, she was meant to come on holiday with us for a week next week but at this point I’m cancelling her ticket and we’re done, SO text her 10 hours ago and no reply, no trying to meet up, nothing. I feel justified in saying I’m done forever (this is not the first boundary cross) but feel like maybe I’m a bit dramatic as I know it’s hair that grows back. AITAH?

For clarity: she is not a hairdresser, she has not cut hair before, my daughter’s fringe is left at about 1/4 of an inch.

UPDATE

MIL text SO tonight with “I said I was sorry”. He wanted nothing more but I made him ask to meet up - to which she replied no thanks I’m not keen on meeting (me), anyway I made him go and got him to bring baby as we won’t see them again for a long time and I didn’t want him to have regrets if anything happened etc. They sat down and had a long talk and in the end they both decided they love each other as they’re family but they don’t like each other.

The reason given was that in her day it wouldn’t be a big deal so she was doing us a favour, the reason she just left is because SO was shouting, the reason she didn’t want me there now is because it’s only about family, the reason she didn’t contact for 2+ days is because she was upset.

We are flying tomorrow without her and I guess I don’t know if/when we will ever see each other again. It’s closure without any closure.