Early stages of a £50 live tournament with 1 rebuy. 12k starting stack. Blinds are 200/400 I have 35k. I'm utg with AK off suit. I raise to 1200. Guy in mid position who from what I have heard is a pretty good player and has around 25k 3 bets to 3600. Gets back to me and I just call as I don't want a big pot out of position. There was one other caller before me too. Flop comes k22. I check so do the others. Turn comes q I bet out 3600 and the pre flop raiser calls. River comes 5. I didn't want to get raised so I just check with the intention of calling. He then bets out 12k and I just panic thinking I can't call 12k it's too much to lose he might have queens or aces so I just fold. I berated myself afterwards for playing so bad and convinced myself that he was probably bluffing and that no half decent player would ever consider folding there. I always get scared to put chips in and think too much about what I'll have left if I lose. But then what realistically can he have there that he is beating me with
Am I a terrible player?

bet fold river

Sounds like you had a plan going into the river and you levelled yourself out of calling because of the size of the bet. If your plan was to call then I would probably stick with that as I don't see how the Q helped much unless they had QQ, but then you become to exploitable by always thinking your beat without the nuts.

As the other posted said, a bet/fold OTR would make this decision much easier.

It doesn't mean you're a bad player, maybe just need to learn from these spots. Review them, but try not to berate yourself as this doesn't really accomplish much