Demi Lovato reveals sister on a news radio show on the morning of March 6, 2013.

Demi Lovato revealed how she felt when she discovered the existence of her secret half-secret on the WBLI New York morning radio show.

Lovato said she spoke to her sister for the first time over the summer of 2012.

On WBLI's 'Dana & Jeffrey in the Morning' show, Lovato said, "I just got to know...I have an older sister that I've never known my whole life. She's in her 30's. She's my half-sister. I talked to her for the very first time in my life around when I turned 20 [in August 2012]."

Demi Lovato added, "I asked her, 'Why haven't you ever contacted me?' She just said, 'Well, because I never wanted you to think that I wanted anything from you. So I've just kind of been waiting to see if you wanted a relationship.' I thought that was so incredible. So I actually have three sisters!"

Lovato didn't give her newly revealed sibling a name, but the older half-sister joins Demi's older sister, Dallas Lovato, 25, and her 11-year-old half-sister, Madison De La Garza, who previously starred on 'Desperate Housewives.'

According to Today Entertainment, Lovato's representative hasn't yet responded for requests for more information on the newly revealed member of Demi Lovato's family.

The first single, 'Heart Attack', off Lovato's fourth studio album is available for digital download.

Demi Lovato is currently a judge on The X-Factor USA that airs on Fox networks.