I think you way overreacted.
She only asked him if there was anything to do around the area. Big deal. And the comment about the dogs is incredibly reasonable. What if her kids, being kids, stuck a hand through the fence because they saw "DOGGIES!" and wanted to pet them? Kids do that crap all the time. You sure can't blame the mother for wanting to make sure they aren't going to take a finger off.
Seriously, few things destroy a relationship faster than being all crazy jealous every time someone looks at or talks to your SO. If you can't trust him to answer a message from an old HS acquaintance, something is really wrong there. Relax, you'll drive him away if you act like the relationship police all the time.



