What do you wish your parents did differently?

What do you wish your parents did differently? My kiddo is 7, and has a stutter, along with some breath regulation struggles. He's been in speech therapy for about four years. He doesn't like to talk, which makes sense. He doesn't have friends, because kids his age just ignore him. He also doesn't have patience for kids who can't speak smoothly, so it's hard for him to connect with anyone at all. ​ The social aspect breaks my heart, but even more than that is how little I know of what's going on inside his mind. His says he is always angry, and that I "built him angry." He hates being asked about himself, hates listening to others if they talk too long. I've started writing him letters in a notebook in hopes we can have a better rapport that way. What can you tell me about growing up with a stutter? Is there anything that you remember that made you feel better, things you wished people had done differently, anything important that I should know about parenting a kid who feels so isolated and angry because of his speech?