After that kind of raise I would probably wince and fold. The bet on the end is fine; there's a lot of stuff they would likely call with, and if they raise like they did here, it's probably only something that beats you... unless this is ever done with something like 2 pair or an oddly-played over pair? I would think they'd just call with it, though.

At those stakes the chances it's a pure bluff are so slim I'd give them a cookie if they were bold enough to push me off that hand with air.