Life surely is now complicated enough without bringing up the past. That is really about all there is to say about that. You now are left with how much help your Mother requires and how much of that help you are either willing or able to give her. Leave the past alone. There is no way to change it, no way to make it better. The best anyone can do about the past is to apologize for the pain memory of it causes. If that past was so painful for you that you feel you do not wish to or are unable to participate overmuch in your Mom's life at present, that is understandable, but it need not be stated. That only leads to argument which is never won or lost, only painful.
Your profile says Mom lives in her own apartment and is suffering from a Dementia. Dementia is a progressive desease. Some it progresses slowly others fast. My Mom it was monthly changes. Your Mom can no longer be reasoned with. Her ability to process what is being said and comprehend has been greatly effected. Short term is going or gone but that long term is still there. What I suggest is getting some thick skin. Chalk it up to the desease. No it won't be easy, old hurts will come to the surface. Just go along with her. Say your sorry. Don't argue.
There will come a time when Mom can't live alone. Please start planning for that. Take advantage of resources in your County and Community. Ur County Office of Aging should be able to help.
If that past was so painful for you that you feel you do not wish to or are unable to participate overmuch in your Mom's life at present, that is understandable, but it need not be stated. That only leads to argument which is never won or lost, only painful.
There will come a time when Mom can't live alone. Please start planning for that. Take advantage of resources in your County and Community. Ur County Office of Aging should be able to help.