I apologize for butting in on a Chirstian thread but I'd like to point out something.
It's not the behaviour the kids come to see as normal and acceptable, it's the
person. After all, they don't witness any of the behaviour.
So maybe this is a chance for a lesson. If you view homosexuality as a sin you can point out that here is a well-respected, well-loved and
good person who is commiting a sin. It shows that sin isn't something only bad people do but something we're all capable of . I certainly know too many people who think being Christian or being "good" somehow means they're incapable of sin and so never critically examine their own actions.
It also shows how it's possible to love and respect someone even through their sin, something a lot of people can't do these days but something I think kids do naturally. You'd have to be clear with your children on your values but that ain't a bad thing.
This isn't easy stuff to think about. My only thought for the OP would be that Jesus was pretty clear on loving the sinner. I guess my question would be, how could you express love in this situation? (of course my own answer is that you couldn't do it by not going but that's me

)