Lol, I'm no fan of CB's. In my mind, she was the one who was acting poorly with respect to her current R, and her judgment about how to interact with a male in great pain is questionable. But, nevermind that...
Given she stopped the R, it would be VERY inappropriate for her to come up to you, your STBX, and your mom. Hopefully, she will behave better than that. In that case, there is no problem. There is no reason for you to initiate contact.
However, apparently history suggests she may check up on you.
If you are confronted with interacting with her in a social situation, how about simply,
To CB: "your D did very well, excuse me." To mother: "Say, I've been wanting to ask if ...." Or, To STBX and mother: "See you back at our seats in a couple..."
