6 handed on pokerroom, full stacks.

I'm in small blind with [9c]. UTG is very loose preflop. Not so sure about his postflop play yet, but think he might call to much.

UTG limp, 2 folds, Button limp, I raise to 10$. Both call (big blind folds).

Flop 32$: [4h][3h] Ugly, but I need to find out where I stand. I bet 15$ (probably mistake #1). I do sometimes do this halfsize bet with the holy nuts though...

UTG calls (I'm thinking Q or high heart...)

Turn 62$: I check, he bets 25$. I think he's probably on a FD, but scared of looking like an idiot if he is on some kind of Q...

I call. River is . I check, he uses all his time then bets 100$ (=nut flush).
I fold, cursing for playing this hand like a donk

Looking forward to your comments.