As best you can, set limits and hold boundaries with him in a collaborative, rather than combative, way

"Both are in the middle childhood phase (eight to 12 years), meaning they are competitors within the same developmental stage, which can lead to the type of tension you describe."

My mum usually picks up my two children from school once a week, but says she won't do so until I apologise for my behaviour. I'm hurt that she has taken sides and is using childcare as a form of leverage.

"The transition from primary to secondary school can be particularly challenging for children. Many are still in transition mode because we are only a few weeks back at school, everything is new, and a period of adjustment is needed."

Her only-child status may be more ‘correlation over causation’ when it comes to her struggles. Many solo-children can turn-take and share, and many sibling-children will struggle just as you describe.

Reading is nurtured and developed in school from ages five to eight years (and beyond, of course), which means your son is still very much in the 'learning to read' (and specifically learning to read with fluency) phase of his education.

"So much is written and said about the critical early years of our children’s lives, and again when they reach those tricky teenage years, but very little attention is given to the middle stage of childhood, the years between eight and 12."

Since then, he has become very withdrawn and finds it hard to go outside even to play with friends, as he doesn’t feel good enough now

You could talk to the coach about your concerns in a calm way, without venting. The coach could clarify the club’s structure, focus, and goals for the team, enabling you to make an informed decision about whether your son should stay.

"The best thing you can do for your children in the meantime is to take care of yourselves and each other. Focus on maintaining open communication and connection, and ensure you have a support system you can activate for yourselves: Friends, family, professional therapy, etc."