Dear Loveable,
You have every right to refuse to participate in any type of physical intimacy, which you feel uncomfortable with.  You have the right to honor yourself, your body, and your moral choices without guilt or shame. First, I would simply explain to your fiancé how you feel about this topic. Explain to him how uncomfortable you are and that it is not something you want to do or will do. If he continues to ask you to do this, you will need to make a decision about whether he is the right man to become your husband. When a man truly loves you, he would never ever pressure you to do something you feel uncomfortable with or badly about.