What about religion?
Most of the main Christian denominations, and most other mainstream faiths, have taken the view that sexual activity is only appropriate between members of the opposite sex who are married to each other.
The Catholic Church do not criticise homosexuals per se (it is ok to be gay), but oddly, instead criticise the loving actions of homosexuals - what they limitedly describe as "homosexual genital acts". You may be lucky to have an open-minded member of the church in your parish/area, and talking with him or her could be of some comfort to you.
At this point in your child’s ‘coming out’ – their happiness and well-being is of great importance. So discussing this issue of religion with your child may be of some benefit to you, as they may have already given it some thought.