Sorry, couldn't see the rest of my post on my iPad. Had to open another to finish lol.
Again I don't know how long you were at the table, just going to take the time to write about player observations and assumptions people make, since I'm bored.
Too many times players make the mistake of putting reads on opponents they have little or no history with. I've been guilty of this plenty as well. How many times have you been called down with top pair, semi weak or weak kicker, saying "how could he possibly call here, he should have folded," only to see that if you'd have just waited to make that type of play until you had time to build a little history with this player that he's not the one to try to push off hands.
Not picking on you, but in this example how long have you been at this table? How many hands have you actually seen the villain show? A lot of times players don't realize until its too late that they really haven't actually seen many or any showdowns from a player they are trying to read.
Also players tend to be too narrow on their player personalities. I see so many throwing around TAG and LAG, but rarely breaking them down further or into other personalities. There's a big different between a TAG that folds medium pairs in this spot and ones that flat looking to set mine. If this particular villain has show that he likes to set mine, you have 7 on the flop and a 9 on the river. Earlier you asked why it isn't possible that he floated a K flop. Its very possible that he floated, but an 8, 9, T, or J is the turn that you don't want to see if he floated you.
Had you thought about the turn after he flatted your 3b and then flatted your cbet? Was it in your mind that an A, K, J, T, 8, or 9 on the turn would be bad cards? An A here is probably the best card you can see, since it doesn't really change anything unless he floated you with AQ. What else is he floating you with? He either has you beat on the flop or the turn brought a card you didn't like. He shoved, but what if he hadn't? Would you have checked behind? What range did you put him on that this turn didn't help? You can beat AQ, AJ, TT, JJ, Axs and 88. Axs being the only realistic shove here for those hands. You lose to all Kx, 22(doubtful), 77, 88.
In the end, you played for the effective stack with middle pair on a middle set heavy board with and overcard in your opponents range against a player that if the only info you have on him is that you labeled him as a TAG, probably isn't the best place to get your money in. Especially in a low stakes live game. Just my two cents.