I think there's a way to disable notifications when a specific number calls or text you. At least in Android.I guess I'm a bit lucky. SO never looks at my phone and but in any event, I always keep it in my pocket. If it dings with a text message and if she's nearby she may ask what was that. I'll look at the phone and if it's safe I'll tell her, and on the off chance it's an SP responding to my text I'll just say something like "it's Bob talking about last night's hockey game" or whatever - works every time.
Having sad all that, the SP who texted the OP should be outed so guys can avoid contacting her in order to not get in trouble because of her totally unprofessional approach. .
I also use an app called Dingtone. You can get a number almost anywhere in the world, including most large Canadian cities. Many numbers available for Ottawa or Gatineau. When I google my Dingtone number, it still show up as whoever had that number years ago, not to Dingtone.