I have struggles with a sibling with ADHD.
In what way are you struggling with him?
I think he can't handle stress, and he sometimes loses control of himself.
It's good to be concerned about a family member, but you should be supportive of him. If you think he is doing something wrong, then you should talk to him and give him advice. Try to help him rather than get frustrated with him.
He acts like a little bitch.
I don't think that's the right attitude to have. You need to be supportive of him.