No one in here should be telling her not to get married. That is a major decision that should not be entered into lightly. No one here truly knows the entire situation. She needs to speak with her family, friends, pastor, counselor, and fiance about the situation before deciding whether to marry. It is irresponsible of people to tell her not to get married when they do not even know her. Obviously there are things she needs to think about and pray about. But there are obviously other things affecting her decision making process and her emotions. She needs to seek God and listen to Him. It is ok to give advice, encourage, give things to think about, give warnings, but to tell her not to marry? Where do any of you come off thinking you have the right to give that advice? What if she listened to you and ruined her life? Do you want that hanging over your head? What if God had put these two together? Who are you to tell her to leave?
I hope you pray about the situation and do what is truly in God's will. Talk to your therapist and parents. Talk to your fiance. Talk to your pastor. Do not enter into a marriage that is not the right marriage. But please do not walk away because people you do not know thinks you should.