dont bet inot a paired board with only a flush.

I think you had equity as you stated, but as you said, the river bet was stupid.

the flop is decent

I bet, 3 callers, the guy who 3-bet raised, I raise, one fold 3 callers.

definite bet out but I'm only calling the raise. the raise is from a set or top 2 with a draw of some kind. losing players is a bad idea since if the raise can outdraw you just let bottom 2 and small draws stay in.

you also have only 8 outs on the turn here to go with your runner runner low.

the turn is the perfect card

I bet, 3 callers, the guy who 3-bet raised, I raise, one fold 3 callers.

can't find anything wrong with this

the river fucks you and you know what you should have done, I'll leave it at that

really the only thing wrong I can see, other than the river brain cramp, is the flop reraise, but this is a marginal mistake at the most.