I've been in a committed relationship for several years. In parallel, I've been back in contact with my ex for about a year – it escalated into mutual exchange of intimate photos. She never knew I had a girlfriend the entire time. I had blocked her on social media from the start so she'd think I wasn't using it anymore. She still kept reaching out via SMS or email. I wanted to end it multiple times but never followed through. The situation has now come to a head: She left her husband and wants to meet up and get back together. I don't want that – I never seriously pursued that from the beginning. Shortly after, I received this message from her:

"Word on the street is that you're renovating half of your grandparents' house with your girlfriend and moving in together. Apparently she's not exactly slim either. Gotta love living in a small town?"

The information most likely came through her cousin, who is loosely connected to my social circle. She now knows I have a girlfriend – but not who she is, and she can't know her. That's currently my only protective factor. She knows where I live and where my parents live. My specific questions:

How do I end this for good without angering her enough to escalate? How do I prevent her from showing up at my place or my family's? How do I prevent her from contacting people in my circle and letting things leak out? How do I protect my girlfriend from finding out?

I'm aware this situation is my own fault – still looking for the most realistic way out.