Transcript for Actress Selma Blair opens up about 'tears' and 'relief' of MS diagnosis

An ABC news exclusive talking for the first time on camera about her diagnosis and has -- so much has changed for her. She starred in Hollywood blockbusters for more than two decades. You are about to hear how it has affected her voice but her spirit is unbreakable. An emotional return to the red carpet for actress Selma Blair, known for her roles in cult classics like "Cruel intentions ""Legally blonde" and "The sweetest thg" revealing her multiple sclerosis diagnosis last October. The 46-year-old attending Sunday night's "Vanity fair" Oscar party with the support of her customized cane. How can we make canes chic is in F patent leather. I spent time with her at her home, just days before her big night out. How are you doing? I am doing very well. I am very happy to see being able to just put out what being in the middle of an aggressive form of multiple sclerosis is like. So my speech is, you'll notice, I have spasmodic dysphonia right now. Reporter: Ms is a chronic often unpredictable disease of the central nervous system made up of the brain, spinal cord and optic nerves. Wouldn't it be funny if I fell in? For real. Not real. It's interesting to be put it out and say this is what my particular case looks like right now. Let's go back. When you were first diagnosed what initially went through your mind? I cried. I had tears. I wasn't -- they weren't tears of panic. They were tires of knowing I now had to give in to a body that had loss of control. And there was some relief in that because ever since my son was born, I was in an Ms flair up an didn't know and I was giving it everything to seem normal and I was self-medicating when he wasn't with me and I was drinking, I was in pain. I wasn't always drinking but there were times which couldn't take it and I was really struggling with how am I going to get by in life and not taken seriously by doctors. Just single mother, you're exhausted, financial burden, blah, blah, blah and I said I need to go to work and I have to stay awake. I dropped my son off at school and before I had got home I had to pull over and take a nap. I was ashamed and I was doing the best I could and I was a great mother but it was killing me and so when I got the diagnosis, I cried with some relief like, oh, good, I'll be able to do something. Reporter: Struggling with symptoms for years prior to her diagnosis, Selma sought out the help of Michael J. Fox who has lived with Parkinson's disease for nearly 30 years. I said I don't know who to tell but I'm dropping things, I'm doing strange things. He got in touch with me and we began a conversation. So he really helped me plus I was like -- I have Michael J. Fox's email now. Really he gives me hope. How difficult was it difficult to share with your son? Not at all. I always want him to feel safe, never responsible for me but he had already seen that I was falling and doing things and I was always laughing and he'd imitate me and be like that's fine but don't do that out of the house. People will think you're a jerk so I have to tell him that I have something called multiple sclerosis. And he almost cried and said will it kill you? And I said, no, I mean we never know what kills us but this is not the doctor telling me I'm dying. He was like, oh, okay. What gets you through those difficult days. I get in bed and don't move. You have to. You can't do it all. It's fine to feel really crappy and say, I got to -- and my son gets it and now I've learned not to feel guilty. What are doctors telling you? The doctor I saw he said within a year I could have at the time he said 90% of my abilities back. So this is -- this is to say let's meet again next year and see if I'm better. If I'm not and I can still have a conversation that's good enough and I want to see. I want to see for other people and I want to see for me and see where I am. I was a little scared of talking and even my neurologist said no, no, this will bring a lot of awareness but no one has the ability to talk when they're in flair up but I do because I love a camera. You got a date. I'll see you in a year. Okay, okay. I can't wait. Beautiful, beautiful. Wow. I mean, she is incredible. What an example she is setting for her son but also for everyone in the way she's telling her story. When I told people I was going to be doing -- tears of joy because for her to share her story as she has and she has touched a lot of people and you have to know that Ms is unique. The symptoms present themselves differently in different people and she's finding inspiration from her experience and even wants to -- she's really proud of her blinged out cane and also designing her clothes because she's unable to button so she wants to -- she's appreciative of the clothing out there but it's not cool enough for Selma Blair and others. She's brave. So brave. There's times when she's more symptomatic and less symptomatic? Exasperation she's going through. What's frustrating she knew something was wrong. And the doctors couldn't figure it out. Finally had the mri and the diagnosis and probably living with it for many years and presents itself in more women than men. We had a great time. See it tonight on "Nightline" then "Vanity fair's" feature on Selma is live on their website and the March issue is on newsstands now. Still a working actress. She's still out working and has a Netflix show and appreciative of the fellow actors and producer working with her and understanding what it is to live with a active condition like that. We hope a lot more work is coming.

This transcript has been automatically generated and may not be 100% accurate.