"I wasn't ready until now," the actress, 34, told People magazine about being diagnosed at the age of 20 during her "Sapranos" stint.
"You'd think that after all these years, somebody would be settled with something like this, but it's still hard to accept."
Sigler added that in the past 10 years, she has started to see symptoms from the disease.
"I can't walk for a long period of time without resting. I cannot run. No superhero roles for me. Stairs? I can do them but they're not the easiest," said Sigler, who married Major League Baseball player Cutter Dykstra last week.
The actress shared photos from the wedding in Palm Springs, California, with People, along with how she kept working over the years while living with MS.
"Sometimes all I needed was like five or 10 minutes to sit and recharge but I wouldn't ask, because I didn't want them to be suspicious," she said of being on set. "Things are manageable now."
MS is "an unpredictable, often disabling disease of the central nervous system that disrupts the flow of information within the brain, and between the brain and body,” according to the National Multiple Sclerosis Society website.
Other actors and celebrities like Jack Osbourne have been open about the disease and how it affects their lives.
"I'm at a point in my life with my son, with my new marriage, it's a new me,” Sigler told People. “I don't want to hold a secret where it feels like I have something to be ashamed of or have something to hide.”