You may very well be prohibited from marrying outside of the Christian Faith, as there are canons against it. Your best bet is to talk with your priest and be honest. Love is important, but love does not make you compromise what you know is true. Truth and Love go together.
Other questions for you to consider: Have you talked to your parents about it? Your Christians freinds? Most importanly, have you discussed this with your spiritual father? Have you talked to God about this in your prayers?
At some point it might come down to the question, what is more important to you.....marrying this man or being faithful to God? Whom will you serve? Who will ultimately fulfill you? Who loves you most?
"But seek ye first the Kingdom of God, and HIs righteousness, and all these things will be given unto you." If you truly put God first, you will know what to do.