Parent of a child just diagnosed

Hi all, my child has just been diagnosed with Autism.  We know in school he masks and is clever academically, however he struggles emotionally and has meltdowns when he comes back home. He struggles with his friendships, he gets bullied, physically and he will go back to the person that has hurt him because he doesn't understand he needs to stay away. We've tried explaing it to him but I'm wondering if anyone else had experienced this and what they did that worked.

He struggles with going to the toilet at school and needs to be told to go because he will leave himself so desperate through the fear of his work not being complete. He's very slow with writing so doesn't like doing to the toilet if he's in class that requires writing. Hoping to have a meeting with the senco regarding support in school.

He's not taking the diagnosis well. We've explained its not a bad thing and its there to help and support him now. I've also bought some books to help him understand what the diagnosis means and that others see the world like he does. 

Any advice appreciated. 

Thank you Blush