I'm sorry you are both going through this. I don't know if you would find it helpful to hear a positive story?
The same thing happened my DS12 in his first year. Though he was putting on a brave face, it affected his confidence and he couldn't help but take it personally (he thought he was being excluded because there was something wrong with him). It escalated to a point where we had to tell school, and it subsequently escalated further 😳. It was quite traumatic at the time, and I worried about him endlessly.
Fast forward a year, and he is thriving again and has a new set of better friends. His old friends continue to be dickheads to other children, but now leave him alone. He can now see their behaviour towards him was more about them than anything he had done wrong.
We found things got better for DS when he started some team sports which helped him build new friendships, and Judo for confidence building.
We had spoken to the parents at the time, with mixed success. Some parents just cant believe that their child could be capable of bullying, and that was frustrating, because it could have been nipped in the bud if parents had been onside. They are frosty with me now, but that's not a big deal.
I would let the school know about things but tell them that your DS doesn't want any action taken. The info you share may help the school build a picture, and for all you know, they may be doing similar to other children.
While it was awful at the time, it gave my DS the opportunity to make new and better friendships that I dont think he would have made otherwise. He now knows what to look for in a good friend, and some behaviours that he would never tolerate from a friend again.
I hope things improve for your DS very soon x