Tina Knowles penned an incredibly sweet Mother's Day letter to her "incredible daughters" Beyonce, Solange, plus close family friend Kelly Rowland and niece Angie Beyince -- read here! Credit: Kevin Mazur/WireImage.com

Sweet mama! Ahead of Mother's Day this Sunday, May 10, Tina Knowles penned a sweet open letter in TIME to her daughters Beyonce, Solange, close family friend Kelly Rowland, and her niece Angie Beyince.

In her letter to "Beyonce, Solange, Kelly, and Angie," Knowles, 61, wrote that she considered all four girls as daughters. "Every day, I wake up thinking about how much I love, admire and cherish each of you," she gushed. "Writing this brought to mind all the ways you guys have been such a blessing to me. When I’m feeling sad or not-so-cute or maybe a little sorry for myself, and you all include me in your group chat and tell me how hot I still look or how cool I am. Maybe you send me a crazy YouTube video. What actually works best is a cute photo of my grandchildren."

Knowles said her girls helped her through her split from Mathew Knowles in December 2011. "I remember slumber parties after my divorce, when we watched old movies and ate a lot of ice cream. I felt so loved and supported. The roles were reversed, and it was ME who needed nurturing," she wrote. "I remember my first date when every one of you weighed in on what I should wear. The obvious things about all of you are apparent. You are all strong, beautiful, intelligent and smart businesswomen. You are so much more than that. You are all kind, generous and you treat people well. You are all amazing mothers, wives, daughters, sisters and friends. All of you have total self-respect."

The designer then wrote blurbs to each girl. "Beyoncé, I wish people could see how you are when you’re not in front of the camera or on the stage," she wrote to her world-famous eldest daughter, 33. "How compassionate and kind you are to people, how you look them right in the eye when you speak to them." The proud mama acknowledged her daughter's many accomplishments, saying: "Yes, you are a huge star, but you have somehow managed to stay grounded and humble in the wake of all your success."

Knowles then turned her attention to Solange, calling her little one, 28, her "rebel warrior." She noted of the singer, producer and designer, who famously attacked her brother-in-law Jay Z in an elevator after last year's Met Gala: "Always defending the underdog and fighting for what you believe in. I remember you, at 10 years old, started a petition to remove a bad teacher, and your dad and I were so proud of you."

"As tough as you are," Tina mused of Solange, "you will drop everything to take care of someone you love."

The family matriarch also gave a shout-out to Beyonce's childhood friend Rowland, 34, who came to live with the Knowles family at a young age. "Kelly, I know without a doubt that you were a true gift from God," she wrote. "You came to live with us when you were only 11 years old. You were the sweetest, most kind person I had ever met and you still are. You are also a true survivor. You never give up."

Her niece Angie — the Vice President of Operations at Beyonce's company Parkwood Entertainment — was also included in the loving tribute. "I always trusted that you would look out for and protect Solange, Kelly and Beyoncé, and you did!" Tina wrote. "You still do sometimes. You are so smart and perceptive, and you see through bulls--- right away! You’ve always had our backs. Our own family fixer!! You know I call you Olivia Pope!!!!!"

Tina wrote that her proudest moment of all with the girls was her wedding last month to Richard Lawson. "All four of you said in your own words that I taught by example, and that I helped to make you the women you are today!!!!" the newlywed mother wrote. "That was truly my proudest moment!"