Has anyone managed to go no contact with one parent but not the other?

Back story: After years of mental and physical abuse off my mum the final straw for me was her saying the reason for the physical abuse was because she couldn’t deal with my grandad dying (her dad, it was an awful 6 months watching him lose his fight with cancer). I was about 12 at the time, shortly after this my parents moved me 200 miles away to the middle of nowhere as a last attempt to control my behaviour. I will admit I was an awful teenager but looking back im definitely starting to understand why. I’m now 22 (female) and have moved back to my childhood home away from my family. Since then my mums behaviour has become more visible and I’m finally done with it.

Now my dad, is no doubt my favourite person in this world. He still to this day will do everything he can at the age of 70 to help me and without him I wouldn’t have been able to move away. But, he stood by and allowed my mum to treat us both awfully. Honestly I think he’s terrified of her, I remember one time when I was 15 my mum was drunk (she’s an alcoholic, drinks 2/3 bottles of wine a night) she punched me, threatened my dad with a knife and let our family dog out (I found him he was safe). The next morning? Everyone acted like nothing happened and we went back to acting happy family.

Fast forward to recently. Tuesday night I was told via my mum in the old family group chat (she’s blocked so not sure how I seen this message) that my childhood dog we had since I was 8 was being put down Wednesday morning. This was expected but I was devastated as I didn’t have enough time to drive home to say goodbye. Wednesday I got up for work, was having a hard morning but my bestie and boyfriend were both there for me (I work from home). I had asked my dad to keep my updated and he said he would. In the meantime, I received a card in the mail from my mum asking me to unblock her and talk this out. Not one apology, not one part of her feels any remorse for the trauma she’s inflicted. By lunchtime I heard nothing so called my dad to find out my dog wasn’t put to sleep but was just having a check up. I had a mental breakdown almost immediately. Everything I had been keeping in and all the punches I had in just those 24hrs alone was too much.

So.. I’m so sorry for the long post and thank you if you are still reading. My question is has anyone been able to successfully cut off one parent and not the other when they are still married and living together. I really don’t want my mum in my life anymore but don’t want to lose my dad.