Christina Applegate was devastated when her daughter told her she misses "who you were before you got sick"

Speaking on the Let's Talk Off Camera with Kelly Ripa podcast, Christina said: "I don't get up in the morning with that, I get up because of her. She's the reason I'm still here and trying."

"But she did say to me, and we got into a big thing the other day, and sorry Sadie, but it has to be said. She said, 'I missed who you were before you got sick'. That is just like a knife to the heart because I miss who I was before I got sick too. Very much."

Multiple sclerosis is a chronic autoimmune disease that affects the brain and central nervous system.

Last year, Christina - who has been married to Sadie's dad Martyn LeNoble since 2013 - admitted she was really struggling to come to terms with her illness.

She told the Messy podcast: "It's kind of scaring me too a little bit because it feels really fatalistic, it feels really 'end of'. I don't mean that, but I'm trapped in this darkness right now that I haven't felt in probably 20-something years. I don't enjoy living. I don't enjoy it. I don't enjoy things anymore."

She later added: "I'm good. Does that take a little bit of the pressure off of all of you? I'm good. Let's address it. We are going to address it. It's a moment. It's a thought. It's a feeling. I was talking about some dark stuff I was thinking and feeling.

"I think it's important to be able to say these things," she continued. "I dare anyone to be diagnosed with MS or any kind of chronic illness that has taken who you were prior to that moment and go, this is great. You know? No.

"You have moments of feeling like this is tiring and I don't wanna do this. But you do it, and by having friends like you and my beautiful friends that I have, by saying this out loud, it releases the pressure in the balloon, man."