“I knew you were a ten, and now the world knows,” Gellar wrote on Instagram.

“You make the rest of us believe that we can do anything.

That we can never give up.”

Selma Blair and Sarah Michelle Gellar attend the 26th Annual Race to Erase MS Gala at The Beverly Hilton Hotel on May 10, 2019 in Beverly Hills, California.

Selma Blair and Sarah Michelle Gellar.Axelle/Bauer-Griffin/FilmMagic

“Thank you for that gift,” she continued.

“And speaking of gifts [Selma] your love and friendship is the greatest gift.

I love you Blair.”

“I have been so fortunate to be loved by you.

It is a gift I will cherish forever.

I love you so dearly.

Thank you for being by my side on another journey.

Here’s to many more.

“With a chronic illness, you do need special considerations.

My body is taking a hit.

It’s way too much for my bones.

There’s just way too much bone trauma and inflammation… that I do not want.”

Blair was diagnosed with multiple sclerosis in 2018, and has openly discussed her sustained treatment for the condition.

She also chronicled her treatment in the documentary featureIntroducing, Selma Blair.

Dancing With the Starscontinues tonight on Disney+.

Check out ourdaily must-see picks plus news, celeb interviews, trivia, and more onEW’sWhat to Watchpodcast.