How much to VB on rvr w/ set? NL100

[EasyAs1-2-3]

Villain is 50/9/2 over a couple hundred hands but all mined. Just sat at table.

Hero has $100, Villain covers.

Hero is dealt 4[img]/images/graemlins/club.gif[/img]4[img]/images/graemlins/spade.gif[/img]

UTG folds, Hero(UTG+1) raises to $3.5, Villain(CO) calls, BTN folds, SB folds, BB folds.

Flop ($8.5): 6[img]/images/graemlins/heart.gif[/img]3[img]/images/graemlins/diamond.gif[/img]4[img]/images/graemlins/diamond.gif[/img]
Hero bets $7, Villain calls $7

Turn ($22.5): 8[img]/images/graemlins/spade.gif[/img]
Hero bets $18, Villain calls.

River ($58.5): 10[img]/images/graemlins/spade.gif[/img]
Hero($71.50 behind)....?

Spots like these always seem to confuse me. I feel like we have 3 options - shove, bet 1/2stack, or bet tiny. I've always leaned towards shoving more so than betting about 1/2stack b/c I think it gets called more than 1/2 as much of the time. I seem to ignore betting real small in general. This is one of those spots I've never had a great understanding of. Any input is welcomed.