I am one of 7, 4 girls, 3 boys, and a single mother. Back in 1990 I began caring for my father, (separated from my mother). At first it was weekend visits with my daughter, then aged 10.
Over the next year these visits increased to 3 then 5 days a week. None of my family wanted to know!.
In February 1991 I had to put him into hospitaL, aged 83, since he was so frail and weak. He died 3 days later.
His partner of 25 years refused to leave their home but would stay alone so my very good friend stayed with her overnight. Her own family refused to help! That weekend was horrendous as I faced my family, arranged for Nan to go into temporary care, tried to comfort my daughter, and grieve for my father.
I then got accused by Nans family of taking things from their bungalow and that was the final straw. I gave them the keys to the bungalow and told them to get lost, oh so politely!
Once the funeral was over I found I was still visiting Nan, her only visitor and sh became very demanding, despite being in a Home permanently. (She had refused to move when her temporary stay was over!). For the next 3 years I struggled with a full time job, a teenage daughter, my increasingly hostile family and Nans increasing demands.
I walked away from my family during that time and a year after Nans death I became seriously ill with ME/CFS. (20 years later I still have it).
When my mother developed denentia and lost her sight I shamelessly used my illness to limit my interaction and would visit every 3 or 4 weeks. I couldn't stand the stress, anger and name calling I received.
Now 15 years later I can rebuild a relationship with 2 sisters and one brother.
As hard as it is, you have to put yourself first. Your health is vitally important to you. It's hard, and others, including Social Services will lay guilt on you to try and keep you caring full time.
As others have stated, it sounds very much like your mother is suffering a form of dementia, symptoms very similar to my mother, and now my elder sister. Get professional help for both of you, because you will benefit knowing that your mother is being cared for.