fold pre.call river

"When he bets the river I think we're beaten. Am I too nit now to think this? "

I don't really think you're beating much (s)he's betting for value here. So, I think the decision comes down to how you think the pool is playing. If you think they're value heavy in this spot, I'd fold. If you think they're overbluffing, definitely call. If you think they're playing GTO, mix leaning toward call?

I can't really say how the 25NLz pool is playing in this spot though, but I suspect microstakes is a bit value heavy, so the fold is fine.

EDIT: Also, I'd probably fold pre.

seems alright to fold pre or river without reads, I'd tank a lot on the river to make good decision.
Villian should bet this type of flop quite often and AQ possible candidate for check back sometimes, so he shouldn't have many better hands for Value (A4s isnt a concern, you block it heavily as A7s, 44 and 56 is more concern here lol).
Guess if I called it pre I would call river or bet turn and decide river. With your line he can bet AJ for value here

Ok so we're defending AJo preflop oop against a 3bet.
And now, we're looking to fold our hand on one of the best board we could found ?
So why did we called preflop ? What did we hope ? what was the plan ?
I'm not folding here even if I'm going to muck.

Especially against unknowns, to me AJo is an horrible hand to defend OOP against a 3b.
And even against players we might know, I'd rather 4b than defend especially OOP.
In most case AJo will be a fold against a 3b

AJo plays poorly oop vs a balanced 3betting range and/ or tight 3betting range. Villain needs to be 3betting pretty wide to make a call profitable. Also his 3bet size is quite large.

Fold or 4bet preflop.