AceShowbiz -

Demi Lovato revealed she has a half-sister she never knew until recently. Lovato spoke in an interview with web radio station WBLI on Monday, March 4. The actress revealed, "I think my fans would be excited to learn that I just got to know. I have an older sister that I've never known my whole life."

The "Princess Protection Program" actress, however, did not reveal her half-sister's name. "She's in her thirties. She's my half sister and I talked to her for the very first time in my life around when I turned 20," said the singer. Lovato has two other sisters, Dallas Lovato and Madison de la Garza.

Lovato seemed puzzled as to why her half-sister never contacted her. "I asked her, 'Why haven't you ever contacted me?' " said Lovato in the same interview. "And she just said, 'Well, because I never wanted you to think I wanted anything from you. So I've just kind of been waiting to see if you wanted a relationship,' " the pop star continued her story. Lovato added, "I just thought that was so incredible. I have a third sister that I didn't know until this (past) year."

Lovato is preparing an album which will be released later this year. In February, the singer-songwriter released lead single "Heart Attack" from her fourth album which is still untitled. "Heart Attack" debuted at number 36 on Billboard Pop Songs Chart. Earlier this month, a lyric video of the song was released, garnering half a million views on her official VEVO channel.