I recently started probation and I took a pissed test and I know for sure im going to come out dirty the thing?

is that I have this bipolar sis that is on a cps case and had her kid taken away temp, the thing she opened my mail and called my probation officer/cps and told her I smoke pot in front of my kids, so cps contacted me and they want to meet with me and my husband. We both are excellent parents he works daily has his own business and well im a stay at home mom I dedicate all my day to my kids and we are so attached. We are so very discrete that no one in our house knows or even suspects, very family oriented and this lady is coming this week my husband wants to be as open and honest as possible lets say that we are, what can happen and will it be confidential or will they tell our family members and the person who will have temporary custody while we get clean. We are not addicts our kids are very well taken care of well dressed always clean our house is always clean as well and we look very decent. Help me I don't want to put this loving drama free family or my kids through this...