OP I have name changed to tell you my story. It's very similar to yours.
My parents split when I was 18 months. I am now late 30s. What i know of the split comes from court papers, my aunts and conversations I over heard and things I remember.
Mum and dad split. Dad paid all the Bill's as his job housed him. They got divorced, dad have mum the house, which she sold and used to get a smaller hour mortgage free (lots if equity).
Mum would take us our when dad was meant to be coming and seeing us. Then he went to court and had organised visits. Except she told him that she would kill herself if he came and took us out. So we would come back and find her. Then she told him, she would kill us and herself if he came (she admitted this a few years ago during an argument).
She the broke into his home and smashed it up with me and dbro sat in the back garden. I remember sitting in the garden. She was sectioned and the released to the care of my grandparents. When she was 'better' we moved into the house she bought. She had lots of relationships with men and one more short marriage.
My dad was always whispered about but you could ask mum. She simply told us he he left us for someone else, but in more vulgar terms. Turns out that wasnt true either.
He always came to events like my first holy communion and things. I remember my mums family asking her and her telling them he was coming but she would only allow him to stand in the church balcony and wasnt to come near. I remember looking up wondering which man was my dad. She cut up all the photos of him and I didnt know what he look like.
Shortly after my first holy communion, he got in touch and again and asked her to see us. She allowed it. I now know she said he could see us, if he got back together with her only. So he did. He didnt feel court could help. She had been sectioned and they allowed us to go back with her. My grandparents used to pretend they lived with us. Looking back we should have been removed. She has serious mental health issues but will not acknowledge them. I grew up in a very troubled environment.
My mum and dad got back together and it was awful. I would be woken 2 or 3 times to her screaming and swearing at him about things that happened in their marriage the first time. I would call my grandparents to come and sort them out. Or go round and pick the doors, so dad couldnt leave.
I left home at 19 and loved in with my husband to be. Who was abusive and I was with him until I was 35. The relationship with mum has been up and down. I do get on with dad, but struggle to understand why I didnt see him for 10 years when he loves me as much as he appears. Exh raped me and my mum took his side. Dad, who now is more mum carer totally enables her to keep her calm. And wouldnt take sides at all. He wont leave her now as she is disabled and still mentally fragile.
I am now no contact with them and mum is exh housekeeper. She even baby sits, his new girlfriends kids.
She always told me my dad made her mentally ill. It wasnt, her father was an abusive drunk and she thought the sunshine out of his arse. That's why she is so ill
What I am saying is OP, you arent alone. It is confusing. You grow up with one story, then realise it's another. You are left drifting.
I believe my dad did all he could. This all started in the 80s. He even got back with her to see us as he couldnt see another way out.
I am very damaged and seeking counselling. I don't feel that I have ever been loved by anyone. I have tried to make contact with my dad, but mum monitors all his devices (phone, tablet) and the minute she knows I have been in touch she bombard me with abuse.
I have had good times with mum. But always on her terms. And she has admitted things when she is well.
But I dont think you or I will ever get the full story or know if our fathers did enough. But I do know the we have to keep moving forward. Counselling helps unravel our feelings about it. But its hard not knowing the whole story.
I am sorry you are going through this and it will get better. 