Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
If you mean by "Fiancé" the woman to whom you have proposed marriage but you have not yet established marriage contract with her, this is not a wife to you. So you cannot divorce her. But if you mean a woman with whom you already established a marital contract but have not yet had sexual intercourse with her, then this is not a Fiancé, this is a wife. Now if you divorce her thrice while in acute anger, then the ruling of this divorce depends on the degree of your anger at the time of pronouncing divorce. Ibn Al Qayyim divided anger into three categories:
1) When the man is angry but means what he says. This divorce is effective.
2) When the man loses his senses completely because of anger, becoming in a state where he does not perceive what he says. In such a state, there is no doubt that divorce is invalid.
3) The third situation is where the person is in a middle stage. His anger is not clearly defined. In this case, the most sound evidence is that divorce is invalid. So, try to figure which of the above three types of anger were you in when you pronounced divorce.
Now, if you think what you did was an effective divorce, then you should know that the majority of scholars including the four Imams, the majority of the companions of the Prophet (Sallallahu Alaihi wa Sallam) and the majority of those who followed them are of the opinion that divorce three times can be done in one expression. So, if this is the case your wife is now forbidden to you until she marries another man has sexual intercourse with him and get divorced from him. only then you could remarry her fulfilling all conditions of a valid marriage. Allah Says (interpretation of meaning): {The divorce is twice, after that, either you retain her on reasonable terms or release her with kindness.}[2:229]. The opinion of the majority of scholars is the most preponderant and the most supported by evidence. However, some scholars believe that saying: "you are divorced three times" at once is considered only one divorce. So, for these scholars if this is the first divorce or the second one, the husband can return his wife to wedlock life as long as her Iddah has not expired.
Allah knows best.