My child competed in a kick boxing tournament today

So my son who is 10

Years old competed in his very first ever kick boxing tournament. This is a sport his paternal grandmother teaches and also his dad so they are huge into it. I personally have never been a fan of contact sport where people get punched in the head. Working in a hospital I see way too many brain injury patients. Well anyway watching this tournament was the hardest thing I have had to do with my son, with every blow to the face and kick to the body I could feel my eyes tearing up, o could see my son holding back tears as he was trying to act tough since he had such a huge audience, when the fight was over he ran to me and completely broke down which is so out of character for him. This kid barely cries, I knew he wasn’t having fun. His dad and his grandma were so proud of him and gave him so much praise but when we got home he told me in private that he hated the tournament and never wants to compete again, he told me he hates kick boxing and hates getting hit which is totally understandable. But having a father and a grandmother who live and breath kickboxing it’s hard for him to just quit. They’ve already registered him for upcoming tournaments and tryouts, he’s voiced that he does not want to do these but he’s only met with “oh you’ll be fine” I’ve said I don’t want him doing these and I get the same answer “oh he’ll be fine”. I’m not sure what to do, I have my family telling me that this is child abuse and to not allow him to compete but it’s a lot easier said than done. I need some suggestions on this one. I also have a toddler daughter who at the moment absolutely loves to watch fights and spar with her daddy so of course he cannot wait to get her into it. But I don’t want her doing that sport either. I’d rather something more calm like ballet or piano or even soccer. I’m so stressed about this, I’d never forgive myself if one of my children got a brain injury from this.