Jamie-Lynn Sigler Recalls Nights She ‘Fell Apart, Terrified’ Fearing Her Son Beau 'Was Going to Die' (Exclusive)

• Jamie-Lynn Sigler's 11-year-old son Beau was hospitalized for 33 days with a rare autoimmune condition known as acute disseminated encephalomyelitis

• The Sopranos actress tells PEOPLE that while in the hospital, her son lost the ability to eat, walk and talk, and she was "terrified" he would die

• Sigler says her experience living with MS helped her be a strong advocate for her son, and helped Beau, who's back at school and playing sports, in his remarkable recovery

Jamie-Lynn Sigler has learned to live with pain since being diagnosed with multiple sclerosis when she was 20 — but nothing prepared her for the kind of anguish she faced last summer when her 11-year-old son Beau was hospitalized with a rare, life-threatening autoimmune condition.

"Those were the hardest days I've ever had in my entire life," Sigler, 43, tells PEOPLE. "It was probably the most helpless I've ever been."

Their crisis began last July after her "healthy, active" son suffered a week of high fevers and headaches that culminated in his being unable to urinate. "He was screaming in pain," The Sopranos actress says.

Beau was admitted to Dell Children's Medical Center in their hometown of Austin, Texas, and diagnosed with a rare autoimmune condition known as acute disseminated encephalomyelitis, or ADEM, which causes inflammation of the central nervous system and can develop after a viral or bacterial infection.

Over the next two weeks in the hospital, "he got worse every day," Sigler says. "He lost his ability to walk, and then to talk. Then he couldn't eat or move his mouth." He lost 25 lbs. "There was nothing recognizable about my son."

Doctors put him on a 24-hour IV of epinephrine to keep him alive because the inflammation in his spine and brain prevented him from regulating his own blood pressure and heart rate. "My husband and I would look at each other like, "Is this really happening?'" Sigler says of her husband of nine years, Cutter Dykstra. "Truly, we thought he was going to die."

For more than a month, Sigler stayed at the hospital by Beau's side while Dykstra cared for their younger son, Jack, 7, and she drew upon her years of experience managing the challenges of MS.

"It was wild to watch my son have neurological issues that mirrored mine in very many ways," she says. "My experience understanding the body and inflammation and the brain helped. From 6 a.m. till 8 p.m., I was on it. I was a coach. I would speak to him and tell him he could do it." But, she says, "the nights were when I could fall apart and just be a mom and be completely heartbroken and terrified."

Sigler relied on family and friends for support, including her MeSsy podcast co-host Christina Applegate. "She was there for me in a really scary moment. We sat in prayer together."

Asking for help doesn't come easily to Sigler. "My friends joke that on my tombstone it's going to say in quotes, 'I'm fine.' But for the first time in my life I was actually able to accept help because it wasn't for me — or it didn't seem like it was for me in that moment — it was for Beau," she says. "To realize how loved and supported you are, it's something I'm going to take with me for the rest of my life."

And then, 33 days after he was admitted, Beau was able to walk out of the hospital. "The care that we received, the attention that every family receives, was unparalleled," Sigler says of Dell Children's.

Related: Jamie-Lynn Sigler’s 10-Year-Old Son Beau Leaves Hospital 33 Days After ‘Nightmare’ Diagnosis

At first, "we were just in a constant state of gratitude." But, she says, "there's still a road of recovery." Beau is back in school, back on his baseball team and is working with a personal trainer to regain his strength. "There's some residual things physically we deal with, and because of what he sees me deal with, he knows I understand. I know it's hard to not be able to do something that you used to be able to do."

The psychological toll of the trauma can be an even greater challenge. Although Beau doesn't remember anything from his hospitalization, "mentally he went through something profound and he's trying to figure out how to integrate that back into life and still be the 11-year-old little boy he was," Sigler says. "When you have a near-death experience, there's an intense amount of gratitude you have for life, and he constantly wants to express it, which is beautiful. He wants to go up and tell everyone he loves them and how amazing they are. But for another 11-year-old, that's not how you do things."

She's had to adjust as well. "My son is different than the 10-year-old Beau that entered the hospital in July," says Sigler. "We joke, calling him Beau 2.0. The person that's really benefited from what happened this summer is my little one, Jack, because they don't fight anymore!"

Beau is also learning guitar and has developed a love for songwriting: "It's been how he channels his emotions."

Stress can exacerbate a disease like multiple sclerosis, but Sigler says helping Beau recover has actually given her strength. "Sometimes when you take the focus off yourself and make yourself a service, your body shows up for you," says Sigler, a spokesperson for Novartis who developed a guide with the drug company to help others manage life with the degenerative neurological disease. "There's been no big fallout. I am okay. I'm not struggling physically like I think a lot of people anticipated."

Related: How Christina Applegate and Jamie-Lynn Sigler Are 'Helping Each Other Through' MS: 'We Both Needed This' (Exclusive)

And, she says, she's been inspired by watching her son. "I saw the way a body can heal, and that was something I needed to see. And I saw Beau's commitment to his healing. That's added another layer of discipline I've had for myself and my health."

Sigler, who's in the process of writing a memoir, says that as traumatic as the experience was, it "slowed our family down in such a beautiful way. We are so present with each other. There's just not a lot more we need than being at home, just the four of us."

Read the original article on People