I'm angry with my friend because he asked if I have a mental disorder
Why did he ask if you have any condition?
because I'm so very exhausted all the time
You should be talking out your problems with your friend. Otherwise it could lead to avoidable misunderstandings.
Yeah, I know, I'm just working on it.
It's good you realized you need to have an honest discussion with your friend in order to let him know about what is going on with you.