Why do you jump so often to your LC's sex life? It's not the first time that it's came up.

She didn't have to tell you she was going - maybe it could have helped, but maybe she had her reasons for deciding not to give you a heads up. There was always a chance that you wouldn't be working, or that she wouldn't run into you. She may have been trying to avoid your reaction to her being somewhere with her daughter.

I gotta say that I'm proud of your LC for telling you that she's done with the conversation - she has no reason to discuss her personal life with you and clearly doesn't want to and doesn't appreciate whatever prying you might have been doing.