Wow. I'm so sorry you have to deal with this TuffGirl.
My ex stalks me here too (and God knows where else) although I don't have the proof you have. I opted not to change my username as well. This isn't new behavior for my ex but for whatever reason it still shocks me. I've decided, like you, I will not keep it from continuing on my journey of recovery.
To my ex: if you're reading this, get a life.