when you know that your immediate family will never truly love you or your other gay relative. it really hurts to know that love is conditional to them.
I think some families will never be able to accept someone being anything other than straight. I don't think it necessarily means they love you any less though. I could never be honest with my mother, I did tell her I was bi once when I was much younger but apart from that one time, we've never discussed it. I've had a steady boyfriend for a while now so she probably thinks it was just a phase. If she knew even half the truth she'd probably disown me!
My mom to a T. She'll never accept me as I am today, even though she's okay with my siblings not being fully straight and my older sibling being an atheist. She'd disown me. She's always had ideas in her mind on how I "should" be, and that's not as a bisexual pagan woman. I love her but I wish she'd let go of that crazy idea of how I "should" be in her mind. It drives me bonkers. I'm not that person, I'm me.
I'm sorry that you all can't be open about yourselves with your family. Love is always more or less conditional, that's just how humans are, but love is but one factor out of many - even without love it is possible to be accepting and respectful towards people, even if that goes against the grain with you; in the same vein, it's possible to sincerelly love someone and at the same time to disparage them for what they are.