[Q..]

well i think you should have taken control of action on turn, bet 500 when king falls, as played you dont have any clue whats going on really, if he reraises turn i guess you can throw this against tight opponent. If he calls well its still tough, i think its foldable after he called bet on turn, but at least you have got some information, double check from preflop raiser makes anyone start betting with anything.
As played i don't think its foldable. You gave him feeling your empty and allin bet on river from him doesn't look inviting and strong to me.

Btw preflop push is pure +ev.