Matthew 10:37
"He that loveth father or mother more than me is not worthy of me: and he that loveth son or daughter more than me is not worthy of me." (KJV)
As much as I love my (three) sisters, if one of them decides she is gay and proceeds to marry another woman, I would not attend the wedding or send a gift... I wouldn't even "Wish them well," because that would be a subtle and indirect acceptance and blessing of their union.
However, I'd travail in prayer even more for her salvation and deliverance.
SIDE BAR: When my youngest sister was dating (her now ex-husband), they were planning to visit us, but Hubby and I made plans to drive across the county line, so we could say we would not be in town on that date. Why? Because we only had one spare bedroom, and we didn't want to facilitate them fornicating under our roof.