I'm terrified of attending an aerobics class. It sounds stupid I know but I need help. What advice do you have?

I hate my body. Desperately. I hate my stomach and my thighs and my lovehandles. A little back story. I went through a severe round of depression some years back when I was 9. By age 12 at the height of 5’2 I weighed 210 lbs thanks to binge eating. At which point I became anorexic and my weight dropped to 125 pounds at the height of 5’4 aged 14. Now I’m 15 and I’m 5’5.6 but I weigh 157 lbs, thanks to the return of my binge eating habits due to another bout of depression.
My mother has put me on a diet and given me a goal of being a 130 lbs by the end of the year. She’s also trying to get me to attend aerobics classes.
I live a sedentary lifestyle with no exercise as such and barely have stamina.
My mother’s plan is all well and good but for some reason every time she approaches the notion of an aerobics class I feel like crying, which leads to cutting. I’m okay with dieting, but because when I was younger my parents often told me I was fat and berated me, telling me it was my fault because I didn’t exercise enough, I can’t stomach the idea of an exercise class. Exercise has become synonymous with worthlessness and the worst period of my life in my mind. Not to mention that I was born with a calcium deficiency and hence have weak bones, and my hand eye coordination is deeply lacking. School sports is no help either because instead of working with me on my issues my coach just scolds me and gives me detentions or forces me to play with the basketball team and tells other students to make fun of me every time I slip up or make a mistake. And that’s why I’m also terrified I’ll make a mistake in any exercise class I attend.
Yet I hate my body and want to change. I’ve dieted many times before but thanks to my depression I always bounce back to being overweight, if not obese. How should I handle this? Is there any alternative you can give me to an exercise class please? Or some regime or something that will improve my stamina or something so I at least don’t make a fool of myself if my mother forces me to attend one?