Jamie-Lynn Sigler Reveals How She Hid Her MS From the World for 16 Years With a 'Long Series of Lies' (Exclusive)

After living with multiple sclerosis for two decades, it was easy for Jamie-Lynn Sigler to step in and offer advice to Christina Applegate following her own diagnosis. However, one key difference in their journeys is that The Sopranos alum hid her MS battle from the world for 16 years.

In PEOPLE’s exclusive clip from their new podcast, MeSsy—which debuts March 19 and also tackles life's challenges beyond MS—Applegate admits that she can’t believe Sigler kept her diagnosis hidden for so long.

“It’s because I could for quite some time, until I couldn’t,” says Sigler, who revealed her MS diagnosis in a PEOPLE story in 2016. “And then it became this long series of lies. ‘I have a back issue.’ ‘I must’ve tweaked my ankle.’ I got away with it as long as I could until people would be like, ‘Are you limping? Are you okay?’” 

“I was brushing it off because I just didn’t know what that would mean for me to say it out loud and have everybody know,” she continues. “I’ll probably get fired. Who would want me? I had to take a step back and a step away to kind of really reevaluate my life. I really knew I still wanted to act and if I was gonna continue to do that, I had to set boundaries.”

Applegate, who was diagnosed with MS while in the midst of filming her Netflix series Dead to Me, says that’s one of the biggest lessons Sigler taught her.

“One thing you said to me was, ‘Set your boundaries.’ If you hadn’t said that to me, I wouldn’t have been able to finish up the last season of my show and do it because you gave me that power,” she says.

In an exclusive interview with the two actresses, Applegate also tells PEOPLE how Sigler urged her to set boundaries when trying to continue working, admitting that she was initially scared. 

While portraying Jen Harding on the Netflix series, Applegate says it was “not an easy job” due to MS and she had to tell showrunners that she couldn’t stand or do a lot of walking for many scenes.

Sigler says she was “in awe” of how much Applegate was able to do while dealing with difficult symptoms of the disease and that she was glad she could help her throughout her journey.

“What I wanted to give her was tools and things that I've learned that have helped me. So first, I told her, ‘You need to set up your boundaries. You need to explain what you can, what you can't do so that there's not another layer of stress.’ And everybody wants to help. Just with a disease like this and an obligation of being an actress on a set, you have to explain it to people, and then it can become a rather seamless operation. But you have to be able to explain what you need and what you don't need.”

“We try to explain to people, but honestly, they'll never understand it,” Applegate adds. “I've worked under conditions of having a 104 fever, or I danced on a broken foot on Broadway for a year. Those have an endgame. One day that foot's not going to hurt anymore, and the fever's going to go down. This is forever. And it's really hard to explain to people why you're breaking down. You're breaking down because it's like that finality of it, and that this is it. You don't get better.”

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Each episode of Sigler and Applegate’s podcast  MeSsy provides an unflinching yet humorous take on living with MS — as well as the broader demands in life that the actresses face every day.

"We would talk on the phone for two hours, and we'd be laughing and crying and we were like, 'This is helping us. Let's record this. Let's do it,'" Applegate tells PEOPLE.

Featuring conversations with famous friends and costars like Martin Short and Edie Falco, Sigler adds that MeSsy isn't just "about the specific experience we're having. It's us facing something hard and it's about figuring out how to still push through. We are sharing the deepest parts of ourselves."