The actress candidly opened up about her painful labor and the worry she felt about becoming a mother

Bringing her son into the world was not easy, but Selma Blair can’t imagine one without him.

The actress used Instagram on Thursday to celebrate her son Arthur’s 8th birthday, revealing that she was heartbroken she would not get to see him on his special day.

“I slept two hours. There is a pain. In my head. In my throat where the tears start. I want to smell him. Tell him I am so proud of him. Hold him,” she wrote, next to a photo of her son cutting his mom’s hair. “And I will. Just not on his birthday. Which is today.”

She candidly recalled his difficult delivery, revealing the intense pain and stress she went through with an induced labor that lasted 37 hours.

“It was a painful induced labor. He was weeks late according to doctors. I felt fine. He wouldn’t listen. And there was still fluid. But I was pressured and agreed. Defeated,” she revealed. “The inducing was horrific and no dilation. Full labor with no dilation. for 37 hours. I finally asked for an epidural. I was so at their mercy. And I had to protect him. I was scared of motherhood.”

Blair, 47, was scared she wouldn’t be “a good enough mother” for her son, who she shares with ex Jason Bleick, regardless of the reassurance from her friend who drove two hours to stay with her during the labor.

“He was born at 1021 this morning. July 25,” she continued, explaining that she had to fire a doctor mid-labor who wanted to have her deliver Arthur via caesarean section. “Jason cut the cord and said he looked like me.”

“And now my kid can cut his moms hair and make jokes and assure me just by being him that I am good enough,” Blair concluded. “Even if we aren’t together for this birthday. Which makes tears well, I know he is happy with dad , dancing and playing on the beach later today. What more could I really ask for. Happy birthday. My son. I love you oceans, mama.”

When Blair was diagnosed with multiple sclerosis (MS) nearly one year ago, she tells PEOPLE that she was honest with Arthur about her new challenges — and is constantly impressed by his resilience.

“He’s had to endure a lot; he’s seen a lot,” Blair exclusively tells PEOPLE in the cover story of the latest issue, including watching her fall down stairs or rush to a bathroom if she’s feeling sick.

Selma Blair and Arthur Saint
Credit: Michael Buckner/Variety/REX/Shutterstock

Watch the full episode of People Cover Story: Selma Blair streaming now on, or download the PeopleTV app on your favorite device.

But Arthur doesn’t view his mom’s weaknesses negatively, she says. “He says, ‘Mommy’s not sick. Mommy’s brave.’ ”

Blair was recently surprised to learn that Arthur enjoys having her visit his school, telling his mom that he loves it because she makes the other kids laugh.

“I had no idea Arthur was proud of that,” she says. “I thought ‘I’m probably an embarrassment,’ but to know I’m not was one of my proudest moments.”

Blair’s new series Another Life launches July 25 on Netflix.