“The Other Lady”
“I like it when you’re here” are words that could warm any babysitter’s heart. However, your heart can come crashing down somewhere near your feet when those words are followed with “Not the other lady. She’s mean and she makes me sit in the closet.” And like the Scooby-Doo gang, the OP just had to investigate.
It turned out that the “other woman” this poor child was referring to was their dad’s girlfriend. After informing the dad, the OP never saw the girlfriend around ever again. Hopefully, that means they broke up and not that he’s not just keeping her out of their home.