Mental game is one of my favorite things to talk about.

First impressions: The stakes you are playing at is beyond your comfort zone. 3betting with AK there feels really awkward to you. Humans in general don't like feeling uncomfortable. But our biggest breakthroughs come from pushing through those feelings. In sports you don't make gains in strength without pushing yourself through uncomfortable training.

Also realize that in live cash games it's tough to practice playing a certain hand. In this case AK out of position facing a raise. You could play 100 sessions and only run into this situation a few times. Part of the reason online poker helped players get better is you could multi table and run into that situation 25 times in a week. So you don't want to be results orientated when you may only run into that situation a few times.

I think someone may of already posted this but you should take a few BI's and use them as "practice buy ins". Don't worry about if you are going to win or lose, just focus on 2 or 3 tactical things you want to work on. It could be 3 betting with AK, making thin value bets on the river, and making more moves on the turn and river (as opposed to just making semi bluffs on flops).

Push yourself, don't worry about making a mistake or looking stupid, that is the only way you learn. Good luck OP!