presto -- isolating an all-in raiser preflop

[M.B.E.]

The table has a nice mixture of weak-tight players and loose players. It's a 10-20 game.

UTG raises all-in. It's folded to me, three off the button with 55. I three-bet. Only the button calls. We take the flop heads up on the side with 7.5 bets in the main pot, 2 bets in the side pot. The button is a tricky, aggressive player with good hand-reading skills.

I flop a set: <font color="purple">K-J-5</font color> rainbow. I bet, the button raises, I call.

The turn is an <font color="purple">ace</font color>. I check-raise, my opponent three-bets, I four-bet, and he calls.

River is a ten. Final board: <font color="purple">K-J-5-A-T</font color>, no flush possible. There's 3.5 big bets in the main pot, 11 big bets in the side pot. What should I do and why? Also what do you think of my play to this point? At the time I believed that my pre-flop three-bet made sense but now I think folding would have been better.

Results later.<font color="purple">