How do you deal with conflict between kids and a child who can't let things go?

[unbreakablemum]

Son is 8 and always had problems when someone hurts him he can't let it go.
He will be angry and emotional and make the situation worse by having a face on him even if other child has been told off and usually shout they should say sorry.

He can't control himself and just keep away from trouble.

He never starts the incidents but his behaviour dealing with conflict makes him look like a troublemaker .
I'm fed up of him shouting at kids in soft play that have hurt him accidentally or on purpose and then causing aggro with the kids mums as he has before now gone up to the mum and complained.

How can I get him to react differently ?

Can you just tell him to tell you and you will deal with it. Of course you do then have to do something, but it could be go up to the other mum and explian you know its an acident but your son needs to see their sons mum is told.