Guys plz help asap

So

Something happened. I should not have done it. My due date was late and I was really struggling with migraines and things so I got an extension. But my friend share her work to me and I had not done my historiography so I just changed the words and used her instead. Ahhhhh I turned it in and it was under 18% plagiarism and that bit was not plagiarized. A month or so later the teacher pulled me aside saying that it had came up as plagiarism on my friends work and she showed me the two documents and the last three paragraphs where pretty much the same a little different though. I freaked out and said I don’t know anything that happened. She was really questioning me and I kept on saying I don’t know she said the other person said she did not know either so this is going to an investigation because they are too similar and to come talk to her if I know anything next period. What should I do, I am really freaked out. She said this has never happened to her and that I turned it in later then the other girl. Should I just wait it out or should I tell her I was just about to ask her if I could do scholarship as well. Ahhhh