Advice on my 8 year old son would be extremely helpful. New to this sub.

Advice on my 8 year old son would be extremely helpful. New to this sub. Hello all. Father to an incredible 8 year old boy. He has adhd and a severe stutter. It seems in the last 2 years to be getting worse. Sometimes he will get stuck on a word and will slam his hands down trying to force it out. He has always loved to read and now will not even read a page. He is starting to be more aware of his stutter and how others view him. He asked my wife a few days ago why his words don't come out right and broke down crying. He has also developed an imaginary friend that he said called him stupid when he stutters. He has an i.e.p. team at school and supportive teachers but he struggles to get even a third of his work done. It's hard on me seeing him so down on himself. He is the kindest,most imaginative kid I know. He lights up a room and I love him dearly. Any advice or resources you can recommend for me and my wife or my son would be greatly appreciated. Thank you.