Madonna fell into "the deepest depression" when her daughter left home.

The 56-year-old singer's eldest child is Lourdes, 18, who is studying at the University of Michigan. Although the artist knew she'd miss Lourdes when she enrolled at college, she didn't expect to be so deeply affected by it.

"My sister said it to me when her son went away. I was like, 'Oh my God, you're being so dramatic.' She was, like, bawling and bawling," she told Ellen DeGeneres. "And then my daughter left me, and I fell into the deepest depression. And I'm always so happy when she calls me and she says, 'Mommy, I miss you,' or, 'I need you to rub my head.'"

It's not all doom and gloom though, as Lourdes has settled into university life very well. She has even met a special someone, who has her iconic mom's seal of approval already.

"He came to our house two weekends ago and spent the weekend with us," she explained. "He's a very sensible boy - young man, I shouldn't say he's a boy. He's intelligent, so I'm happy about that."

That opened Madonna up to a line of questioning about her own love life. She admitted the youngest person she's dated over the last six years was 22, but finds it irritating that people constantly ask about age.

"Until you're walking with a zimmer frame, you can do whatever you want," she insisted.

The star is promoting her new record Rebel Heart at the moment, which is why she performed at the Brit Awards last month. The show didn't go to plan, with Madonna taking a brutal tumble down some stairs when a dancer accidentally pulled her over. Although she's come to terms with the incident now, the star is still annoyed by what happened.

"For the first 30 seconds I got back on the stage, I'm sure I was the angriest matador to walk the planet," she said. "The first thing that crossed my mind when I fell was not, like, 'Oh my God, am I hurt? Oh my God.' I was just like, 'Sh*t, I made a mistake. I want to start this again.'"