I think my daughter is molesting my much younger son

My 11 year old is already in therapy, I have informed her therapist of what is happening and we have a meeting but it’s not until next week. *I don’t really know what I’m looking for here but I’m losing my mind and I feel so torn. Today my four year old son informed me his 11 yr old sister has been tickling his penis and butt until he needs to pee. He asked me why no-one else tickles him there and followed up with how it feels funny but he likes it.My daughter has definitely been going through some sexual awakening, I’ve recently taken her phone away because of the inappropriate googling. I’ve taught her that if she wants to masturbate it’s fine and normal and I thought that would be it. She was molested very early on and doesn’t remember by who. We are a split parent household so we never figured it out but we did cut all suspects out of our lives and she insists it hasn’t happened since.I don’t know what to do while waiting for her appointment with her therapist. I can’t send her to her dads because it will do more harm then good but I don’t want her home right now. I’m very torn and very overwhelmed so any advice at all is welcome via /r/Parenting https://ift.tt/2ThotVT