These were my thoughts. He is a risk to himself having previous tried to commit suicide, and a risk to you - he tried to swerve into oncoming traffic (that's a suicide attempt in itself) and you were in the car when he tried. Your son likely feels at risk, too, at least mentally, otherwise he wouldn't be elsewhere. I'm sorry your family is being so difficult and unsupportive/unhelpful- what terrible things they have said.

He is not thinking clearly, likely because of pain and his body not getting the sustenance it needs, and he sounds severely depressed. He is not thinking clearly at ALL - his irrational or uneducated opinions on psychotherapy and the ER are moot now.

It doesn't matter if he WANTS to go to the ER or not. From what you've posted, he NEEDS to. Call an ambulance if you need to. If he can't get sustenance, is severely depressed, is suicidal, and is a risk to you (he disregarded your safety in the car because of his state of mind), he needs to be hospitalized. If it were me, I would do whatever it took to get him there. Your body can't take much more of this either, it sounds like. You've been caring for him and caring for him, and it's gotten to a point where you can't anymore, and that's not your fault, that's the nature of the situation. He NEEDS medical attention. If you have to have him committed to save him, do it. It may be the tough love he needs to find his right direction.