$200NL full ring.....

Delt KK in the BB.
Folds around to late MP who raises to $6.
Folds around to SB who calls,
I raise to $12.
Everyone folds but MP who raises to $18.
SB calls
I call.
Flop comes A, T, A
MP bets $25
SB calls $25
Whats your play? (Im pretty sure I already know it though)

edit: Fixed my typo caught by givememyleg

I believed him and folded.