The problem here is not everyone in this world in Catholic, and not everyone believes that being gay and having a family is a sin.
Wouldn’t it make more sense to explain that this is the reality and that while we don’t necessarily agree with what others may do or how they live, our only job is to love them?
Much of what you have said in this thread is the knee-jerky kind of reaction I have come to expect from this forum. Sadly, this will not prepare young Catholics for what they will deal with in the real world.
We need honest, age-appropriate discussion, without a lot of rhetoric and judgement, if we are going to raise healthy, happy kids into well adjusted, faithful adults.