If you're confused with some things in this story, then ask it here so I can answer it and make it clear for you :)

For the ones who don't exactly know what the disorder is, I've explained it here so please read it. ↓

Dissociative identity disorder (DID), also known as multiple personality disorder, is a mental disorder characterized by at least two or more different personalities. At least two of these personalities regularly take the behaviour completely over. The original personality often doesn't know about the other personalities (only if someone told him about it) The personalities do sometimes know about the original personality and about each other. The personalities have different characters, have different pasts then the original personality and sometimes look differently then the original personality and other personalities. The personalities all can have their own names. And the cause is believed to be due to childhood trauma (abuse in childhood)

↑
There are so many more things about the disorder but that's all you guys have to know for this story to understand it better.