I think flatting here is best for a few reasons. The original raise was from UTG, so he should have a pretty strong range that will be able to call/jam over the top of you. Also, OMCs and nits in these 1/2 games often won’t 3-bet strong hands (even hands like KK and AA) but will always call any raise pre. Given that I think it’s it probably unlikely you will get through all 3 players.
But as David pointed out, this is a great spot to squeeze. A lot of dead money in the pot to win an a good hand blocks some strong hands. Just be careful – if you get call, you are almost certainly behind and dominated. Best case scenario is getting called by TT.