very tough spot on river w/ Flush

this was another really tough spot for me.
I'm calling this turn only to be able to raise a flush on the river and hope to get value out of 2pr/str8 type hands.

Villain is 34/25/3.8

Do I have to assume that at this level noone ever 3bets here with worse and I have to drop no matter even if I only have to be right what is it around 25-30% on this call?

$1/$2 No Limit Holdem
5 players
Converted at weaktight.com

Stacks:
UTG greenlime22 ($400.00)
CO mortenpokah ($69.45)
BTN YouplaBoum777 ($200.00)
SB aimezhu ($212.20)
BB Hero ($200.00)

Pre-flop: ($3, 5 players) Hero is BB :8c: :tc:
2 folds, YouplaBoum777 raises to $5, aimezhu calls $4, Hero calls $3

Flop: :ks: :qc: :6c: ($15, 3 players)
aimezhu checks, Hero checks, YouplaBoum777 checks

Turn: :th: ($15, 3 players)
aimezhu bets $12, Hero calls $12, 1 fold

River: :7c: ($39, 2 players)
aimezhu bets $12, Hero raises to $42, aimezhu raises to $98

Final Pot: $179

thats pretty gross, but i dont think im folding. esp if hes a retard, which he very well could be.

I like this play all around and am calling. Higher flush may happen, but you're getting good odds to call this. The $12 raise on river looks like he's trying to make some money on the pot with what he thinks is a monster. I think he either has AA or a set. I do not think he has a flush.

blah I can't see doing anything but calling

really gross but i call because of his weird ass river lead

he got the nuts.
the question is I only have to be ahead here what like 25-30% right on this call, so is it in his range to be betting this way with a str8 or lower flush ? Don't think he's ever playing a set this way.

Also, how many of you think that if he had a straight, he would just c/c the river instead of donk leading like this? I guess if I had a straight there I would probably bet/fold in this case.