Рушиться может только то, что до этого ПОСТРОЕНО! Maybe differences in language logics, IDK.
A person is not something that had been BUILT before. So I'd not recommend using the word collapse in its literal meaning here.
Рухнуть can be said about plans, hopes, buildings, strategies, etc. Otherwise, choose another word.

I have checked these word but none of them in meaning "collapse".
They actually don't. They mean "lose their willing to live/energy/willpower, etc."

P.S. Another meaning of "рухнуть" of a person is to fall, dump themselves, as if your legs have suddently become boned.
- Он пришёл с работы и рухнул на кровать как убитый.

But it's not about the psychological state of a person. It's quite physical.