If my fiance and baby tested positive for THC and Child Services is coming to the hospital in the morning, what should I do?

Our relationship is rocky at best. I am considering splitting up with her. She is younger and immature and made the choice to continue using drugs during pregnancy even though I advised against it. That is the main problem in our relationship. I have an 11 year old daughter who I have shared custody with. I hope this doesn't involve her. I am really disappointed in my fiance's decision to continue to use during pregnancy. I personally am not a regular user as it gives me anxiety. I do occasionally smoke when visiting a family member in Denver like once or twice a year at most. Unfortunately, my most recent visit was about a month ago. I am not sure what to expect in the morning but I am not excited about it. I am heading to a drug store now to get a test and see if I am clean. I just wanted to spend time with my son and now I am dealing with this because of my fiance's selfishness.