This sort of problem can be easier to address in a home education environment. If things are overwhelming for your child, you may be able to manage the environment so it is just challenging rather than overwhelming. Then he can cope and learn from difficult situations rather than feeling crushed by them and getting a repeated sense of failure through being unable to meet others' expectations. You can watch closely as he interacts with other kids, intervening more effectively than busy school staff would be able to do, as well as giving him coaching after the fact based on your observations. Finally, outside the restrictive school environment, he'd have a bigger range of coping strategies available to him.
A few examples from my kids' lives and those of their friends:
One seven year old had been removed from school aged seven after he had become increasingly violent toward other children. His mum said that after the pattern had started, a few of the kids used to enjoy surreptitiously winding him up just to watch him flip and get into trouble. At our home ed group, she encouraged him to take some time away from other kids when he felt stressed. He would climb a tree and if anyone followed him, he would ask them to give him some time alone to calm down. His mum kept a watchful eye out and stepped in if anyone didn't listen and give him space when he asked for it. If it was all too much for him, she often managed to spot the signs and take him home BEFORE he erupted, so there were fewer incidents. Other parents got to know him well and spoke to their own kids if their behaviour was contributing to problems. He was a lovely boy. I last saw him at 16, at which time he was making a success of himself. He was very active and hands-on rather than academic, and had had the chance to play to his strengths. He still had quite a temper to him, but he knew himself well and could handle situations with maturity.
My queen-bee five year old took against a boy and persistently chivvied the other kids to exclude him. Once it became apparent this was a serious problem, I started watching like a hawk. I think my kid enjoyed the power trip and was just too immature to empathise with the other child. I didn't manage to nip it in the bud through discussions, so I simply said if it carried on we would have to stop coming to groups and restrict ourselves to one-on-one playdates. I enlisted the other parents to help me watch out for any signs the boy was being excluded. That worked, and my child never bullied anyone after that.
My ten year old and their best friend were growing in different directions as their interests changed. BFF began to fancy boys and wear makeup, while DC still played with stuffed toys. BFF started hanging around with older kids and sometimes mocking DC in order to distance herself from DC - but would then deny doing so and say that DC was still their best friend. In the early months, that was quite painful for DC, so DC decided to mostly avoid former BFF for a while, going to different activities until things had cooled down. I can only imagine how intense it would have got if the two of them had been forced together constantly - like having to share an office with your ex-partner just after splitting up, I guess! A few years later, former BFF had grown up considerably and the two were able to be friends again - not best friends, but mates who could comfortably hang out in groups from time to time.
School can be emotionally exhausting. Sharing a crowded space with the same group of kids every day, being unable to take time out, having few adults or older kids on hand, the expectation of sitting still most of the day: for some kids all of that is moderately stressful and for some it is too much altogether.