My mother was physically and emotionally abusive to me and my brother (and our father, but he passed away in 1980). Our mother was in the beginning stages of dementia at 92, and she and I had been estranged for decades. When my older brother told me she had been in a single car accident (still driving and living independently at 92, her anger fueled her longetivity), and despite her abuse of him back when he was a child too, we decided that we would "take care" of her in her final months/years because it was the right thing to do (for us) because we didn't want to look back on our lives with any regrets.
And, because we have mostly healed from her past abuse (I was 45 at the time, he was 62), we felt that we could handle her emotional abuse, which only increased exponentially with dementia. Even though she tried to strangle my brother while he was caring for her overnight, when she finally passed at 93, we have zero regrets about our decision. We treated her like another human being - not like a "mother", because she sucked as a mother. But as a human being, we felt she deserved to be well taken care of and spent her final year being pampered. ONLY because she was a human being.
My only advice to you is to do what YOU feel comfortable with. You are the only one having to live with whatever decision you make, and there should be NO judgment by ANYONE on that decision. Looking at it that way, my brother and I were selfish in our actions, because after decades of therapy, the last thing we wanted to deal with is any guilt, real or perceived, that we would bestow on ourselves for not taking care of our mother's needs until the end.
I hope this helps. It's a crappy place to be in, I know.