What to do on the river?

[DrunkHamster]

Table is fairly loose passive, none of the villains are anything special from what I've seen.

Paradise Poker 0.25/0.50 Hold'em (10 handed) converter

Preflop: Hero is MP2 with J[img]/images/graemlins/diamond.gif[/img], Q[img]/images/graemlins/diamond.gif[/img].
<font color="#666666">1 fold</font>, UTG+1 calls, <font color="#666666">1 fold</font>, MP1 calls, Hero calls, MP3 calls, <font color="#666666">2 folds</font>, SB completes, BB checks.

Easy call I think, no use raising.

Flop: (6 SB) T[img]/images/graemlins/diamond.gif[/img], 6[img]/images/graemlins/heart.gif[/img], J[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(6 players)</font>
SB checks, BB checks, UTG+1 checks, <font color="#CC3333">MP1 bets</font>, <font color="#CC3333">Hero raises</font>, MP3 folds, SB folds, BB folds, UTG+1 calls, MP1 calls.

Textbook protection I think.

Turn: (6 BB) 4[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(3 players)</font>
UTG+1 checks, <font color="#CC3333">MP1 bets</font>, Hero calls, UTG+1 calls.

Hmm, not sure what his bet means. He could put me on the free card play, he could've made 2 pair, he could've improved to a flush draw... who knows. Either way, I'm not folding, and with my new flush draw I don't want to raise an d blow out UTG+1, so I call. I figure if UTG+1 is on a flush draw I have more equity than him, and getting him to fold would lose this and open me up to a 3 bet.

River: (9 BB) A[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
UTG+1 checks, MP1 checks, Hero...

The decision. It seems a bit suspicious after the donk bet, so the question is, what do I do.