I'm Worried About My Step Kids.

My stepson is 13 step daughter is 8 and other step son 6. My step daughter has been acting weird every time she comes over. Even my hubby noticed. First she was trying to touch her younger brothers penis and has never done that before. She also recently started having random accidents during the day. She keeps touching her privates. The past few months we have had a lot is issues with her having YEAST infections. When she says her teetee itches I took a look. She said "I have a pretty kitty" talking about her VAGINA! Where would a child hear that! I told my hubby. He told her mother. Her mother just shrugged it off and her boyfriend goes, at least she knows what she's got. That statement did not sit well with me at all. Am I overthinking it. Please tell me. My husband is worried about it too.

Update: I just want everyone to know we have contacted CPS. I have no idea what's going to happen from here but I gave all the names I knew and addresses. We are probably in for a huge fight with the mom and her boyfriend but I'm ready for it. I love these kids like my own.