3-betting your AQs more often then not in this spot is recommended, isolating fish with a hand that crushes his range is generally a good idea. I'm presuming that it's a fish because of his strange stack size. Also because it's NL5 and I suppose that the regs there doesn't fold either. As it plays out you find yourself in a very easy spot tbh, you don't need to calculate equity to justify your action in this very straight forward spot.
- You are in position
- You have a fish in the pot
- You are 100+bb deep with 3betor
- You have AQs, which plays very well ip multiway
This also depends on how you feel your postflop game is. If you know yourself not to be that great yet you might consider folding as the better alternative. What it really boils down to here though is you not calling more than one barrel when flopping top pair, if mr 3b keeps firing. It's not harder that that really. Also knowing when to bluff, but I don't think you should be bluffing at all (at least extremely rarely) on NL5? Correct me if I'm wrong.
Edit: 300 hands is nothing. You can get a hunch about the player, but it's nothing when it comes to 3bet and It's really a fart in the universe when it comes to squeezing. Get a few k hands and until then use reasoning and think about the spot presented to you!
Best of luck!