It looks like you weren't thinking ahead enough. First, if anyone calls, you'll probably be OOP with a hand that is decent but not great if you pair on the flop, and not likely to flop many draws.
Second, did you look at the implications of your original bet size? Basically, the more you lead for, the more you have to put in to c-bet or check-call on subsequent streets. And if you get multi-way, as happened, it means even more chips. In the actual case, your half-pot bet was almost 20% of your remaining stack into three opponents with TP and a 10 kicker. Not the worst situation in the world, but a long way from the other end too.
And then, it seems rather optimistic to call off all your chips. So what if he has a big stack? He's risking 25k more to win 20k in the pot. Not awful odds
, but as noted, what can you beat? He knows that a large part of your range is made up of big aces, so how likely is it that he's trying to blow you off AK or AQ with either a smaller A or an underpair? It's possible, but is it likely enough to stake your tournament life on it when you can fold and still have an avg stack? IMO no.
It's also possible he thinks you'd c-bet a hand like KK QQ or JJ, but that also seems optimistic.
I prefer the fold pre-, and second choice, as suggested is making it a smaller amount like 1800-2000. As played, I think it's not too difficult to fold to the check-raise.