My (M24) ex (F23) wants to "check in" on me after she left me for her TA last year. How should I handle this?

A little over a year ago, my girlfriend cheated on me and left me for her TA. I was pretty blindsided- I had no idea that she was even remotely attracted to this guy, or that she was so dissatisfied with our relationship. She refused to be in a relationship with me, and I was pretty much just left alone to pick up the pieces of my heart.<br><br>Fast forward about 15 months: she texts me, wanting to "check in" on me. She "hopes I'm doing well" and wants to be acquaintances/friends. She says she broke up with her TA and is looking to be friends.<br><br>I'm in a new relationship, and my new girlfriend is great. I'm much happier now than I ever was with my ex. That being said, I can't help but feel like my ex is trying to see how much pain she caused, if she ruined my life, or something along those lines. I don't know what her true motives are. I know that I'm better off without her, but it still hurts that she just treated our relationship like it meant absolutely nothing to her. <br><br>How do I (or should I even) respond?<br><br>tl;dr: My ex wants "check in" on me after leaving me for her TA over a year ago. Should I respond to her?