Confusing situation involving recently deceased Mum and father who are divorced

I am asking for advice about a situation that I am in which I am finding very stressful. 10 months ago my Mum passed away. She was terminally ill with cancer and I spent the last three years helping her through until her final moments. It was honestly one of the toughest things I have ever been through and I just feel so sad and hurt by a lot of things. Now, what makes this really hard is that my Mum and Dad divorced 13 years earlier and the divorce was bitter. Dad cheated and this affected Mum greatly. My brother and I were caught up in this and we were both in our early to mid- 20’s so we were adults. Dad had multiple relationships following the divorce but Mum remained mostly single. Dad eventually remarried. So currently where things are, is I am still very much grieving my Mum. My brother is fully estranged from my father. Yes I do sometimes block my Dad as he doesn’t comply with communication boundaries that I prefer to have with him as he makes me feel very uncomfortable. I have been also involved in a long term relationship and the relationship I have with my Dad and how he stresses me out has been a source of arguments for my partner and I for as long as we have been together.

My Dad just makes me feel uncomfortable. He has openly been unsupportive about my career. He talked appallingly about my Mum during her last week before she passed. He forces all of his relationships on to me and I just don’t want to have anything to do with his relationships. My Dad pushes his side of the family on to me. They all treat my Mum the same. They don’t recognise that I am sad. It’s like she didn’t even exist to them and I think my Dad has done this. To boot, my cousin will not even talk to me because she thinks that I talk to my Dads side of the family and she is fully estranged from that side.

I just tonight contacted my Aunty (Dads sister/ side of the family) and she didn’t say anything. Zero concern for me at all. She is in hospital and it’s for knee replacement but she is fine and lucid and there is nothing wrong. Yet she doesn’t ask how I’m doing or how I’m feeling. The moment the nurse brings in her meal she quickly dismisses me and hangs up. It’s terrible behaviour. Really bad.

I just do not know how to interact with my Dads side of the family. It’s Father’s Day tomorrow and my partner is wanting me to be the bigger person and actually call my father which I am very uncomfortable about. I just feel too stressed out about it. My partner is angry with me because I feel like this which is making me more and more stressed out. I just can’t believe that despite all of my best efforts of trying to be the better person and try and stop a pattern in our family of gossip, politics, ego, and disgusting behaviour that I still get treated this poorly. I am as equally as stressed out as what I was during the divorce 13 years ago where all of this started (yes, there is a part of me that blames my Mums illness and ultimate passing on the stress my Dad caused).

As part of my Mums final wishes I have promised that I wouldn’t talk about her passing or anything about her in conversation. But I just can’t help but feel that even when I talk to my Dads side of the family or my Dad that that in itself means that I am dishonouring my Mum.

The worst part is that my partner doesn’t understand how stressed this makes me. Every time I am in contact with that side of the family I loose sleep for nights after the contact and my partner and I argue. My partner says my Dad has been good to me and my Dads side of the family has been good to me and I should be the bigger person not let the behaviour get to me. That I need to show them how I want the communication to go and how I would like to be treated. I have talked about this very clearly but not one of my Dads side of the family nor my Dad respect this at all and it leaves questioning whether I want to be in contact with any of them at all. It stresses me out so much that I couldn’t get my heart rate to slow down nor could I slow my breathing.

I just don’t know what to do or how much more I can handle.