Preflop
Standard open and standard defend against his small sizing. You could mix in a 4-bet bluff from time to time, but at 2NL thats probably a bit to fancy.
Flop
Standard defend.
Turn
Unless you think, this guy is very bluffy, I would strongly consider folding now. You still lose to AX with a better kicker, and now you also lose to QX. Moreover its a very dry board, so its difficult for him to be on a draw, which probably mean, his range is skewed more towards made hands and value.
River
I think, he is very unlikely to be bluffing, so I like your decision to fold. I just think, you could have saved some money by making that fold already on the turn.
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