My fiance found out that he is postitive for hep. B (chronic).I am a nurse. I have been immunized and am immune. What are my chances of getting hep b?

You're fine. Congratulations on your upcoming marriage. You're immune and won't get sick from him. Your husband will want to have his hepatitis B managed. I wouldn't be surprised if this becomes curable thanks to biotechnology sometime soon. Best wishes.
Immune. If immune should not be an issue. Your fiance should however seek treatment for his hep b.