*grunch*

Fold preflop. Small suited connectors from middle position are bad. You said it's passiv. If it's loose, you can play a little looser (i still wouldn't play 65s from MP). When people tend to fold to action though, that hurts your implied odds. That makes playing 65s from MP worse.

On the flop you have a flushdraw and a small pair. You could have up to 14 outs to 2pair or better. That assumes, BB doesn't have Kings up already or a kicker matching one of your cards. With the 3bet there is only a true chance to fold the button. I think you are too optimistic to fold BB who check-raised (!!! not a truely passive move) you (he could be pumping one of these higher flush-draws you are so afraid of) and UTG who has already called two cold. Since you still have plenty of outs and BB could be check-raising TP with a good kicker and not a flush draw, I think the 3bet has some value with 2 callers.

BB donks into you on the turn. That smells like a set or Kings up. Without a read I would not think my 5s are outs, really. Therefore I'd check behind on the river.

Since BB seems to (semi-)bluff bet the turn against a cold-caller and an 3bettor, I'd take a note. Since you probably didn't know that at the time, I'd still check behind.