Avoid over-defending small pocket pairs on wet boards where your equity is fragile and your hand is easily dominated.
Folding is the correct play here. While we have an underpair and a backdoor flush draw, this board is too connected and favors the CO's opening range significantly.
Note: Calling with an underpair on a wet, connected board is a losing play; we lack the equity or robust draws to continue against a large c-bet.
Checking back is fine after the CO slows down. We have no reason to turn our hand into a bluff yet, as we still beat their total air like KQo or AJ.
Folding to the half-pot lead is the only viable move. The board paired, but it doesn't help our specific hand, and CO is now representing a polarized range that beats us.