In issues like this it is vital to keep our house pure. This can be seen Scripturally from Achan's sin in Joshua. I am the head of my house, and what happens there I am in control of.
I refused to allow my sister and her boyfriend to stay overnight once. I have regularly sent people outside to smoke, etc.
I would not feel guilty over this unless the issue of homosexuality means that in the past heterosexual sin has been treated differently. If the son was allowed to bring his girlfriend to stay, but not the daughter, then that would be an issue.
Otherwise, stick to your guns, stay loving (1 Cor. 13, Romans 12) and enjoy Christmas...
Cheers,
Zzub
POSTSCRIPT:
PLEASE NOTE THAT THE BIBLE IS EXCEPTIONALLY CLEAR THAT HOMOSEXUALITY IS A SIN. THIS CAN BE REFERENCED FROM SCRIPTURES SUCH AS GENESIS 1 and 2, WHERE GOD CREATED ADAM AND EVE IN HIS IMAGE, NOT ADAMINA AND EVE, OR ADAM AND STEVE.
IN ADDITION, DEUT. 23.17 SAYS THAT THERE SHALL BE NO HOMOSEXUAL AMONG YOU. YOU COULD ALSO READ GENESIS 19 AND SEE THE SAME IDEAS. IN THE NEW TESTAMENT, ROMANS 1 SAYS THAT HOMOSEXUALITY IS UNNATURAL AND AGAINST GOD AND 1 COR. 6.9-11 SAYS THAT HOMOSEXUALS HAVE NO INHERITANCE IN GOD'S KINGDOM.
Interestingly enough, I don't need to cite references for heterosexual immorality so you can look those up for yourselves.
Thanks,
A moderated Zzubster