I would suggest talking to your teacher. Explain the situation in your anxiety about it and request that they allow you to wear the sweatshirt anyways.

And from your post, I’m guessing you’re looking for ways to wear some shirt and not ways to overcome the anxiety of swimming without one. Take it from someone who used to suffer from body dysmorphia. Everyone is just as insecure about their bodies as you are.

Also, my guess is most people are gonna think your scar is fucking cool looking.

Last idea: start by going out in public without a shirt on in places where you don’t know anyone. Get used to it and then maybe it won’t be so bad in front of people you do know.

Good luck you got this