I'd raise to about $9 or $10 PF. That's pretty standard I think. I like the pot bet on the flop. Villian's play is a bit confusing. Calling a large bet on the flop then leading out for a big overbet on the turn. Could be an overpair or some sort of delayed bluff. However, without a great read on my opponent I would lay this down. You only have one pair. This may seem a bit weak but I try to avoid getting all of my chips in with poor odds after the flop with only a pair even if it means losing out on those few times when I had the best of it.