I suspect that in the very near future my middle-aged daughter is going to tell my wife and I that she is gay. She was raised in the Church of Christ, but left when she went to college, graduated and lives in the college town. We don't get to see her much, she does avoid us. She has had several failed relationships with men, and never refers to any one she knows as other than "my friend," so we stay in the dark. Our question is, what should be our response? In a way we have already lost her, as I have implied, but what should I say at the time? Of course, my prayer is that this never happens, but all signs indicate that it will.
I would assume she has already left the church, this would just clarify why she left. You do have not responsibilities to her, now that she is an adult. Paul said, "I wrote you in my letter not to associate with immoral people; I did not at all mean with the immoral people of this world, or with the covetous and swindlers, or with idolaters, for then you would have to go out of the world. But actually, I wrote to you not to associate with any so-called brother if he is an immoral person, or covetous, or an idolater, or a reviler, or a drunkard, or a swindler--not even to eat with such a one" (I Corinthians 5:9-11). Therefore, tell her you love her and because of that love you cannot support her self-destruction. When she is ready to leave her sin and come back to Christ, your home is open to her. Until that day she is on her own and you will be cutting off any remaining contact with her.
It will be very hard to do, but it will show the strength of your convictions and the severity of her sin.