Hello there, I disagree that this is not about you and your fiancee. It needs to be about all three of you: you, baby and fiancee.
I understand your reluctance to tell your fiance. Trust me: been there, done that, got the t-shirt.
However, Robert is telling you the truth. The worst thing you can do for this baby is to go cold turkey and keep the info from your OB-Gyn & fiancee. Worst case scenario is that you miscarry due to the withdrawal (yes, that can happen & if you need confirmation, Google is your key). Or, your baby could have developmental problems ESPECIALLY if you undergo withdrawal during first trimester.
I know you are afraid your fiancee will be angry that you told him you were off the
Suboxone; however, how angry would he be, and how guilty would you feel, if you lost the baby because you were too afraid to tell him and your OB/G about the meds? I can promise you that the OB will understand. If they don't - you need a new one. I can't promise you what will happen with your fiancee, but for the sake of your baby everyone needs to know the full picture to make the right decision.
I don't mean to scare you but the only thing that is not an option here is for you to go cold turkey off the Suboxone and to hide this from your fiancee and doc. You know what - you have a problem. But you are not a bad person because of this problem. You are a good person by doing the next right thing when faced with a difficult situation.