Hellllppppp dating a man twice my age

You all always seem to help me when I'm in need. So I'm in a very serious committed relationship with a man twice my age. I'm 20, he is 40. We are actually eloping soon. Bad news: NO ONE KNOWS WE ARE DATING (on my side of the family). I'm scarred to tell my family out of fear of disapproval. How do I tell my family??? HELP