Friday Riddle

Remember, NO GOOGLING or SEARCHING the Internet allowed and good luck !!!!

RIDDLE: The case had been closed for almost one hundred years. William Pritchett and his sister Olivia, had died of a strange ailment. Their arms and legs shook violently, they had severe abdominal cramps and fever. On her deathbed Olivia accused Holly, the maid, of poisoning her and her brother. Holly told a different tale; of William and Olivia's descent into madness and her efforts to cure them through herbs and vitamins. Holly was put on trial and convicted. When she died in jail of a similar sickness, it was assumed Holly had poisoned herself through carelessness and the case was closed.
Now, it was opened again as the relatives of those long dead battled in a civil suit. Holly's great nephew, was suing the wealthy Pritchett family, for the pain and humiliation his family had endured. He claimed William had gone mad and poisoned both Olivia and Holly. Forensic Psychologist Stella Mavis had been called in to determine the sanity of people who lived and died before she was born. Finding little information in the ancient file, Dr. Mavis traveled to the Pritchett mansion to look over some old belongings, stored in an attic.
When she pulled up, Detective Davis was already there, talking to Maya Pritchett, daughter of William's cousin.
Maya greeted Dr. Mavis, then showed them to the musty attic. "Most of this is William's." said Maya. "This was his workshop. Some woodworking but he mostly made those." She pointed to a large stack of moldy fur hats on a trunk. "It was his hobby, but he didn't feel it was a proper hobby for a high class gentlemen, so he worked on them up here. Underneath them is a trunk of Olivia's." Maya disappeared down the stairs, eager to get out of the stale air.
Detective Davis began looking through boxes of William's clothes. Dr. Mavis moved the furs away and looked through Olivia's trunk. Wrapped in a scarf on the bottom was a little diary. Dr. Mavis leaned against the pile of hats and read:
January 4th: I have been shopping in town and helping William, it's been so much fun to help make the hats! I don't like Holly. When she serves our tea, I am always helping William in the workshop, and she glares at me. She's just jealous of me.
May 18th: Today I was in the garden and I saw Holly's face change into a spider! Holly hates me, and I think the spider means she is going to hurt me. My tea tastes bitter, and Holly said it was medicine, but I don't believe her. I can see things for what they really are now and I think William can see them too.
September 20th: I am so tired of the medicine in my tea. I always feel sick after I drink it. Holly says I must stay away from William. She has turned on him and says he's dangerous! This must have been what the rainbow I saw yesterday meant when it said she would betray us...
December 12th: I ache and I have no control of my legs. But it's ok! I can fly! So can William, he says the unicorns told him we need to leave this place. I am so excited!
Dr. Mavis couldn't make out any more, but she didn't need to. "Davis," she said, "Let's go. I know what happened."

What happened to Olivia, William and Holly?