Please read to the end as I feel context is necessary here.
My mum recently stopped speaking to me and my sister, after sending us both a message saying "would it have KILLED you both to wish your stepdad a happy birthday? I am very pissed off with you both and so disappointed". My sister made some remarks about it not being at the top of her priority list and I basically said "you asked me to be civil with him many years ago which I have been, but I won't pretend to have a relationship with him and I'm annoyed that you expect that I would". She then replied with "I give up", left the group chat she has had with us both for years and a week later still has not spoken to either of us since. She's currently away on a 3 month holiday with her husband and due to return soon and we don't know what to expect, if she intends on discussing this any further or not speaking to us at all (my sister is getting married this year and she's supposed to be giving her away).
CONTEXT
My sister and I have never had a good relationship with the man. My other family members don't like him much and they don't even know half of the real reasons we don't like him.
These reasons range from things such as telling us as kids that our real dad didn't care about us (not true) after we all moved overseas for this man's job and left behind the rest of the family and life we'd always known. He would buy branded foods for him and my mum, keeping them in a special "adults cupboard" that we weren't allowed in, leaving the more basic/cheaper things for us.
I was a bit of a rebel as a teenager (nothing outrageous) but a punishment for sneaking out to meet friends was for him to board my bedroom windows shut, remove the door from its hinges, give me one single outfit, a "uniform" to wear for a month, ground me, make me sweep dirt in the garden, remove all of my cosmetics, appliances etc.
When I got my first job, there was a really bad storm and no public transport where we live, so my mum asked him to give me a lift (5 mins drive, I would usually walk it). He refused to let me out of the car until I paid him £20 as he said that's what a taxi would have cost.
All of the above may sound simply like strict parenting and nothing too outrageous to some. But it goes on....
When I was grounded and no door on my bedroom, at 14 year old I once woke to him sitting on the end of my bed in the middle of the night. When I opened my eyes he RAN out of the room. I felt physically sick and scared of what his intentions were as I woke up thinking someone was touching me. It was only a few days after he removed my bedroom door. When I finally got the courage to tell my mum about this (after spending weeks sleeping fully clothed after it happened) she just said she would talk to him. The result was I was allowed to move into the annexe outside, despite asking many times before if I could and being told no. My mum then said she spoke to him and he said he was "chasing the cat out of my room"....a room without a door that a cat would just wander back into anyway. There was no attempt made from him to discuss this with me, no conversation ever took place after until I raised it with my mum again years later as an adult.
I'm addition to this, not long before this incident happened, we had a cleaner. She left our house, telling my mum she was scared for her daughter's because she found a camera in the bathroom. This was laughed off by my mum and stepdad and became a running family joke that the "crazy maid" obviously must have thought the black shampoo bottle top looked like a camera.
But then years later, when I was an adult and had finally moved away, my sister tells me she finds her video camera that had gone missing, in their room. She looks on it and there are video clips where he filmed the neighbour through her window getting undressed. It was a series of clips over a few months. It was him filming because his voice can be heard. When my sister told my mum she was devastated and drove with my sister a number of hours to come and stay with me. We thought this was the realisation she needed, but she ended up getting back with him less than 2 weeks later and my sister and I have kept this incident secret from the rest of our family for my mum's sake, which seems ridiculous now.
That being said all of this happened around 10 years ago. There have been arguments over the years, none for a long time, but they have always resulted in us basically saying we will never like him, her playing the victim (which she is in many ways) and us feeling guilty and having to keep the peace. He has spent Christmases with us, I have had him in my home, cooked meals for him etc much to my displeasure.
I had my first child 2 years ago and went through counselling because I refuse to let these feelings be something that affects him one day. Part of that has made me realise it isn't my job to protect my mum's feelings at my own expense, so I am trying to not fall into the same trap again. She constantly refers to her husband as my child's grandad, which I hate, but I haven't said anything about it yet. I am very very close to my grandparents and I don't feel he comes even close to deserving this title.
I've never really spoken to other people about this and I'm keen to hear outsider views. Was I unreasonable to not wish him happy birthday via text when they are away on the other side of the world, considering I wouldn't usually contact him on his birthday anyway? Is it unreasonable of me to let her stay silent and not reach out to try and resolve this? How would you approach this when she returns if either she a) confronts is and wants to continue the debate or b) acts like it never happened?