The 38-year-old singer added to ELLE magazine: "Then I had Blue, and the quest for my purpose became so much deeper. I died and was reborn in my relationship, and the quest for self became even stronger.
"It's difficult for me to go backwards. Being 'No. 1' was no longer my priority. My true win is creating art and a legacy that will live far beyond me. That's fulfilling."
Meanwhile, Beyonce previously admitted she had to undergo an emergency caesarean section when she was pregnant with her twins, because one of their hearts stopped "a few times" in the womb.
She explained: "My body went through more than I knew it could. I was 218 pounds the day I gave birth. I had an extremely difficult pregnancy. I had high blood pressure. I developed toxaemia, preeclampsia.
"And in the womb, one of my babies' hearts paused a few times so I had to get an emergency C-section."