How did this happen?

[Chrimb0953]

Mum and Dad divorced over 20 years ago
Dad was incredibly cruel to my mum emotionally.
Dad has remained difficult towards mum whenever he's in her company and this has been uncomfortable for all around, yet dad tries to use me to find out about when he can, as I think he hankers after her - unbelievable really.
In the meantime my sister married someone who changed her beyond recognition because everything is very much about him and his way of living life, so sister has morphed into a 'mini him' and is utterly unrecognisable. I no longer have contact with either sister or brother in law (or my young nephew), as us adults just don't get along.
Despite showing the utmost kindness and respect Mum has also had massive issues with the 2 of them and now no longer sees them and has been banned from seeing the only grandchild she has, which is obviously heartbreaking.
A such, l no longer feel able to continue a relationship with my dad, when my mum is being treated so cruelly, as I believe my dad shares some responsibility for the situation. This means the relationship between me and my dad has now broken down.

AIBU to feel done with it all? Why do 4 people in a family end up with so much anger and bad feeling towards each other to the point where the family just breaks up? Any thoughts?

I'm sorry for the situation you're in. There are a lot of similarities to my birth family and I currently have no contact with my dad (over 35 yrs) mum (nearly 10yrs) or sister and her husband (4 yrs.)

It is painful but I've had to just look after myself and surround myself with supportive friends. I hope that in time I might be reconciled with my sister, but it's not within my power to do anything more to change that.

Look after yourself OP 🌸

Thank you for reading and for the reply 🙏

Your father doesn't hanker after your mother, he is finding out information so he can continue to hurt her even more. It's what abusive men do. Refuse to discuss your mother or her life with him.

Your sister has morphed into her husband as a way to "hide". She is still hiding from her abusive father and using her husbands personna as a shield. This is what children can do when raised in an toxic household.

Why do 4 people in a family end up with so much anger and bad feeling towards each other to the point where the family just breaks up?
Because there was an abusive, controlling, manipulative, mean person who ruled the house. This is why women should never stay in an abusive marriage for the sake of the children. It hurts everyone in it for many years afterwards.

Take care OP. You were raised in that household. Maybe you should consider counselling to let the past stay in the past, it can be very insidious

@Chrimb0953, I'm on the opposite end of this from you, sort of.
I sought a divorce from my DCs' dad many years ago. It's not relevant as to why. I've always gone with the idea that DCs' will work out what they think of their father without me saying anything, as ultimately he is still their father and I didn't want to hurt their relationship with him.
One of my (very much grown up) dcs has told me recently that their father is no longer in contact with them. DC is very hurt and confused, and second-guessing what went wrong. They are very much in a similar situation to you, which is why I'm posting.
My DC has decided that they will not reach out any more, and will wait to see what happens. I know that this will be painful for them, but cannot argue with what they are planning.
It's not exactly a fit to your situation, but might echo with you.
Go with what makes you feel strong and lifted up. Maybe there is someone in your wider family that can fill that role. And, maybe counselling will help you to work out what you need to resolve this.

Thank you for your input and advice 🙏

Thank you for this