First i would look and see how much they are 3betting overall, then how often they are 3 betting from that position, and i use Notecaddy Edge and have a popup for VS. me stats. so i would look and see how often they are 3 betting vs me.
if they aren't really getting out of line then maybe i lean towards folding, but if they are 3 betting more than 6-7% then i'm probably more likely to 4 bet and probably fold to a shove. i sometimes just call, but don't really want to be playing big pots OOP.
i have gotten my fold to 3 bet number down, but might still be a little high. something i'm really trying to work on lately though.
even at 10nl people will see you fold at a high frequency and go after you a little bit, so i imagine at 25nl you may be running into that a little bit.