This makes no sense

Villain is running 18/10 and this is the first time we have tangled
He seemed competent and then this happened

-I had just pulled off a nasty squeeze w/ Q9s and flushed so I 3bet ~3x in hopes he remembered and 4bet all his big aces/KK/QQ

-Flop could have been bigger i guess but when opp min-donks it's 99% a bluff, amirite...and I didn't want to blow him out

My question is about the river. Im so confused by his line I really just want to call but I dont want to miss value from hands like 88/44/AK...suggestions?

$0.1/$0.25 No Limit Holdem
9 players
Converted at weaktight.com

Stacks:
UTG ($20.60)
UTG+1 ($24.55)
MP1 ($30.15)
MP2 ($9.50)
Hero ($32.00)
CO ($23.95)
BTN ($23.80)
SB ($5.75)
BB ($15.10)

Pre-flop: ($0.35, 9 players) Hero is MP3
UTG raises to $0.75, 3 folds, Hero raises to $2.50, 4 folds, UTG calls $1.75

Flop: ($5.35, 2 players)
UTG bets $0.25, Hero raises to $2, UTG calls $1.75

Turn: ($9.35, 2 players)
UTG bets $0.50, Hero calls $0.50

River: ($10.35, 2 players)
UTG bets $0.50,

WHAT ARE YOU AFRAID OF?!!!!!!?!?!??

also you raised his flip minbet 1.75 when the pot was 5.50.....what is with this betsizing? you should be trying to get all the moneys in on every street