On one hand u pray to the Lord and on the other u say u feel like dying. Dont do that. Have faith.
The way u feel he should repent probably ur fiance must be feeling the same for u. When both of u love each other why get into the question of changing one's religious beliefs.
Talk wd each other and each other's families.
Respect each other's beliefs and faith and accept it. Why try to change the other person.
N hve faith in God. Plz dont pray that he should repent. Instead pray that both of u come together again and are able to lead a happy life.
God bless u, have complete Faith in Him