My aunt doesn't understand boundaries

As the tags said,I'm just adding nsfw just in case..So,my aunt is in her 40's as of now,should have complete autonomy. Right. Sometimes she'd ask me to bathe with her,she's most likely neuro divergent,and as my lovely family decided,not to get a diagnosis because it'd hurt her feelings and doesn't even try to get help for her. Okay,as the bathing situation,I'm 13 rn,not 3 so I, logically would decline but she's always like 'whats wrong with it? We used to do it together',when I was 7. I tried explaining to her why i'm not comfy with that,and she,being very loved would tell my other family members that I'm hurting her feelings which in result make me get yelled at and I'll cry for like,a week. Tried telling them that I'm not comfy but I'd get yelled at again,because I shouldn't hurt her feelings. She doesn't necessarily do anything sexual but still,I dont like it..

Tldr:Aunt asked to bathe,I refuse,tell on me and my family don't like it. set boundary? They don't like it.