Very sorry you are having to deal with hurtful issues from others in addition to your health and welfare issues.
To say we can only control ourselves, doesn't really show the reality of what that means. It can make us feel helpless and hurt even more but the reality of it is that some people mean to be hurtful, not sorry about it and don't care.
To be related to such folks is hurtful to all around them. I believe I can relate a bit because realizing my father turned from what I had formerly known him as a good father who later manifest himself as a very selfish and hurtful person is mind boggling which clouded the ability of many to react properly.
This meant that enabling his bad behavior caused many (including myself for a while) flowed freely for years. To finally come to the realization and remove myself from his list of enablers put me at odds with many. I call them slow learners or just hopelessly ignorant (in denial).
What I learned is that I need to be ok with my decisions. I was not put here on this earth to people please at the expense of searing my conscience. Not my style.
If that means I had to stand up against my father's hurtful actions, then that is what I must do and have done.
It doesn't mean things will be corrected or just. It means I won't enable bad behavior once I am aware of it. If others want to enable bad behavior, that's on them.
I show no favoritism to bad behavior.
I hope this helps you in regards to your mom. I'm very sorry she has not treated you well. There is no easy way to get past this but acknowledging it is a start. My father is dead, can't undo the damage he has done. Those minions he left behind promoting his bad behavior, is my next focus for legal matters. Other than that, I have no empathy for their bad allegiance. I hope they don't stay stuck on stupid but if they choose to, I won't hold their hand.
This discussion isn't experienced by all but for those of us who have experienced such events, we should share and talk this through to help each other out.
LG, please plan for some getting some resolve. Being ok with your decisions will help. It has helped me. Also, I no longer give as much weight to what other people think. I take some of it into consideration when it can help but I throw out the stupid stuff.