Sounds like you are raising a nice son as well as generally doing an amazing job. Grieving a spouse is bad enough without small children in the mix and I salute you.

She will continue to do this if she thinks it's getting to you. I would suggest not reacting (if you do). Perhaps just a 'gentle smile' then carry on about your business. If you feel like a response is necessary you could always try "Yes, and he's not deaf either."