I am hosting my fiancé side of the family Christmas Day dinner...?

Sorry, but when you get married you have to take the baggage of your husband's family. You basically need to suck it up. If you plan to invite your fiance's family you cannot pick and choose who to invite, it is bad etiquette. Maybe there is something about you or someone in your family your future husband does not particularly like... you learn to deal with it.

On the flip side - she is not directly your family so there is a little gray area there. Proper etiquette in this situation is that your brother in law should have asked you if this girl could come along. He should have asked, but even with him asking you should have said yes so the outcome would have been the same.

How can you leave a girl out of the Christmas Day with family? These sorts of things are going to happen in the future. Welcome to the world of extended families.

Your gonna have to stick it out, if you don't like her then just ignore her.

Do you for sure know she's a prostitute and a druggie? If you don't then get your facts right before you judge someone. Anyway if you hate her that much and don't want her around then you need to express it, if you can't express it then stick it out and ignore her..

I would try telling your fiance not to accept those massages, for a start.

Simple. State firmly you do not want her to come to your house and you do not have to explain. Just say you planned for a certain number of people and no more, period. Don't suffer having a tramp over when it is YOUR house; if they don't like it they can go elsewhere.

Work it out one way or another. Or call the wedding off.