Demi Lovato dropped a major personal bomb during a chat with WBLI radio. The 'Heart Attack' singer was in a VIP lounge in an airport after passing through security, doing the phone interview in a quiet place, when she revealed she has an older sister that she did not know about before. Whoa, right?

The singer also revealed that she is slowly but surely building a relationship with her newfound sibling. That's amazing, since not everyone gets that chance.

So how and why did Lovato drop this huge nugget of personal info?

Well, the crafty DJ conducting the interview was actually trying to get Lovato to share details about her love life, which the 'X Factor' judge declined. Lovato reasoned, "I actually like to keep my private life, love life and stuff like that ... I like to keep it very sacred. There are some things you just have to keep to yourself. Unfortunately, I would not like to comment."

She didn't reserve or nix comment about her sister, though, and that seems to be a much more private and personal thing. She only shares serious stuff with Lovatics!

"I have an older sister that I've never known my whole life," Lovato confessed. "She's in her 30s. She's my half-sister. I talked to her for the very first time in my life around when I turned 20." Lovato celebrated the big 2-0 in August of 2012, so this connection is relatively recent and new.

Lovato was surprisingly open, revealing how their initial conversations went. She said, "I asked her, 'Why haven't you ever contacted me?' She said 'Well, because I never wanted you to think that I wanted anything from you. So I've just been waiting to see if you wanted a relationship.'"

Wow. What an honest platform on which to build a new relationship. She continued, "I thought that was so incredible. So I actually have three sisters, that I didn't know until this year."

You can listen to Lovato's big reveal here.

Lovato has an older sister Dallas, 25, and a baby sister, Madison, 11, and now, her oldest sister with whom she is developing a friendship. We wish them the best of luck getting to know one another.

Watch the Demi Lovato 'Heart Attack' Lyric Video