Sounds like you were up against AK?
Its a bit of a tight spot but after the flop I would have first honed in on the stacks I'm up against. A final bet of 24x the BB wouldn't have moved me away from my set...especially at the .50\$1 table on FTP where you'll see people doing this with AA or KK in this spot. I wouldn't rule out KK for the opponent, but like everyone has stated you need to read your gut for what you've seen from this player leading up to this situation. I don't think anyone can blame you for folding or calling so you get sympathy votes.
If you two were table leaders and he bet out 200x the BB on the turn, I'd have to rethink it. I do tend to protect accumulated stacks if I have the 4th Nuts but I likely would have gambled for 24x BB.
I agree with Rios that this is a flop discussion. You got zero information before and after the flop so you've put yourself in a position to know less on the turn. Not only that, but your opponent does NOT put you on a set given how you've played this hand so therefore they are willing to put them in with less than AK I would imagine.....but...was AK the cards held?
