My family does not like my fiancée

My boyfriend of five years has just proposed to me (to which I said yes) and I couldn't be happier. He's a wonderful person who treats me with the utmost respect and would never do anything to hurt me.

 

However, I'm having a problem telling my family about my engagement. Most of my family get on well with my boyfriend but one or two of them seem to have a dislike towards him, despite the fact he has never done or said anything wrong.

 

One member of my family has even said to another through a Facebook message that they hope I break up with him. How can I tell my family about my engagement when I know some of them are going to react negatively towards the news?