Am I a bad person for even thinking of doing this to my Grandma?

Since I was 15, my grandmother’s behavior toward me changed drastically. She criticized me constantly, even for things like not cooking, despite me being perfectly capable. At one point, she spread rumors that I was a lesbian, which caused people to treat me strangely. During a family vacation, she asked for help cleaning but then told me I’d ruin it, and later blamed me for not doing it. The worst moment came when I was blamed for leaving the stove on, slapped in front of my family, and then forced to endure a half-hearted apology. Despite taking care of her when she was sick and barely getting any sleep, she called me useless to my mom the next day. My mom tried to defend her, explaining her behavior as stemming from past struggles, but it only made me feel more isolated. No matter how much I try to help, nothing seems to be enough for her.