Congrats! The A10c hand in that spot I believe is a fine fold ICM wise, you can definetly find a better spot imo. Seeing the hand after and regretting your play is being 

results oriented and to some people ( not saying you ) could change the way the play the rest of the tournament, could be a mental level on yourself.

Thanks v much for feedback.

The main reason I folded was that the opener was a total fish, and as much as I wanted to go after him, he had major bet sizing tells. He had opened UTG for 3.5bb but most of the time had been limping or mini raising. I had to put him on TT+ AQ+ and never folding to a 3bet / Iso raise, and he was one of the few stacks that could really damage me. The reason I felt sick about it was that I had one of those moments of real clarity / intuition that I  had the winning hand (but probably not the best hand) and could have stacked him. It would have looked real bad to the rest of the table but I would have had a monster chip lead. However, I went through the same thinking as you have commented and my head won, and I folded. As it turned out I subsquently stacked him then the other remaining fish in short succession so not really an issue. Just a shame I lost concentration during heads up but I had been playing for about 16hrs so I think 2nd was a fine result. I was v happy with the overall way I had played FT up to heads-up - Big Thanks to TPE for that!

results oriented and to some people ( not saying you ) could change the way the play the rest of the tournament, could be a mental level on yourself.