I figured losing the $10 I had already invested was better than losing $13 more, so....
And I guess maybe I should have made a blocking bet?
PokerStars No-Limit Hold'em, $1.00 BB (9 handed)
MP3 ($100.70)
CO ($100)
Button ($113.45)
SB ($95)
Hero ($104)
UTG ($100.65)
UTG+1 ($101.15)
MP1 ($81.60)
MP2 ($139.50)
Preflop: Hero is BB with

,

. CO posts a blind of $1.
2 folds, MP1 calls $1,
2 folds, CO (poster) checks,
1 fold, SB completes, Hero checks.
Flop: ($4)

,

,
(4 players)
SB checks,
Hero bets $2, MP1 calls $2, CO folds, SB calls $2.
Turn: ($10)
(3 players)
SB checks,
Hero bets $5, MP1 calls $5, SB folds.
River: ($20)
(2 players)
Hero checks,
MP1 bets $13, Hero folds.
Final Pot: $33
Results in white below:
MP1 doesn't show.
Outcome: MP1 wins $33.