The doctor will only tell you that they can't help the patient unless the patient wants help.
My dad has depression, I know he has depression, but he says he's fine, yet he'll cry for no reason, become easily agitated, etc., but still refuses to believe he suffers from depression. I talked to his doctor about it, and actually brought him in to his doctor to discuss it, but he still denied he had depression and even lied to the doctor about his symptoms (while I was sitting there with him). In the end, the doctor told me there's not much she can do unless he wants treatment himself.
In Florida, though, they have what's called the Baker Act where people can forcibly be taken for mental evaluation, but I really don't want to resort to that.
If he won't go to a dr., you might want to go and discuss this with one yourself.
It sounds like Borderline Personality Disorder (BPD) and/or Passive-aggressive behavior. There may be an underlying depression too.
the diagnosis should be made by a qualified psychiatrist.
M4
Unfortunately he has to want help to get help. But if you feel he is suicidal then you can do an intervention and get him into the hopsital where he can get evaluated and start treatment. It sounds like he has anger issues, which can go along with depression, or this may just be his personality. If you think the suicide threats are real then you need to somehow address this with the proper authorities. It sounds like he either needs attention or wants attention, in his effort to always be correct. It's tough when it's an adult who has to decide himself if he needs or wants help, and the family feels he does. If intervening saves his life you need to do it, if not it may cause a big rift in the family. It's a tough decision, I wish you luck and take care.