Am I horrible to say no or ignore asking to help grandma after I was treated?

Background story: I was caregiver for an abusive and racist grandmother. I was treated as a slave working full time and bent over backwards to please my grandmother and family. They wanted more and would verbally abuse me and gaslighted me when I would stand up for myself as if I didn’t have a right to feel this way and stop being so sensitive. I did leave and the best way I knew how and ran off when my grandmother was in the hospital because they would not let me stand my ground. I decided after several times of her trying to frame me for elder abuse was enough. They hired a caregiver but my sister ran them off and was caregiver as she got paid. I did envy the treatment that she gets as caregiver. All the other stuff that I had to do they hired someone else to do it and they tried to pressure me to do it. He doesn’t have to work and gets to keep her own place and stay there two days a week she even gets paid. They said she did not have to pay rent, get a job and gets two off because they had a job. I had to get rid of my place and move in because I allowed them to make me believe I had no choice and me staying there was the reason I had to continue to work and pay her rent. She could be by herself so that I can go to work but it was an issue for me using the restroom on my day off leaving her by herself. She even had a caregiver that came five hours a day but she ran her off.

On my mom’s birthday my grandmother decided to have a bath and she fell.. I know my grandmother to be very manipulative person from my history of herself making herself at the most inconvenient times like when I was supposed to have my day off and my family was going to relieve me for the full day but she just happens to falls and send them home so I was stuck to make it an issue to ever getting a break. The issue is she was offered a bath the days before my mom’s birthday and my sister was going to bathe her the day after and she insisted to bathe on her birthday and fell. She has a host of throwing a fit on people’s birthday. Somehow they tried to divert the blame on the past caregiver who wasn’t there for over a month. My grandmother gets these bruises on her arms. She get a couple soft ones when I was caregiver and my family tried to accuse me stating they know how stressful grandmother can be. It was no big deal when they got worse with my sister saying she is doing the best she can. They said they didn’t start to get so bad until that caregiver came but and somehow she triggered them getting worse even after they left. All of a sudden I am being pressured to be the assistant bathe even though my sister said she would help when she can but it seems like they want me to suffer. It just triggers my panic attacks after what I was put through I know if my grandmother falls the blame is going to divert on everyone else but me but I don’t know what to tell my sister

She went to the hospital and seeing her come home triggered a panic attack. I developed these panic attacks after being her caregiver and they trigger memories of abuse when I was a kid started to come in. I can’t even help for five minutes and told my family when they tried to ask me to help. My grandmother extends her legs with only me when I push her on the wheelchair and I dodge her from getting hit. She tried to make it loo like abuse.

I am trying to protect myself from those situations and I decided I don’t ever want to be anyone caregiver and don’t want to do those roles and jobs that has to do with elder and kids. I made it clear that I don’t want to be alone. I don’t know the best way to say no to help bathing her and I feel bad because my sister helped bathe when I was caregiver because my grandmother didn’t want to take a bath during the afternoon when I got home from work or before I had to get ready for work. The thing is my sister didn’t have to go through what I did.