Is it illegal to hack into and read somebodys facebook and read private emails/chats?

[Lucy M]

I'll make this short a "friend" of mine has been hacking into my facebook account and reading private emails/chats I have with my other friends/family. I've never given her my password never given her permission to use my account never signed onto my account at her home she's never used my computer. The only reason I found out she's been doing it is because I haven't been ignoring texts from her (long story wont get into it) and she kept texting me so I said to a friend of mine on a private chat in Facebook how annoying its getting her texting me all the time and I dont want to talk to her. Well a few hours later this girl is cursing me out in text messages telling me everything that my friend and I talked about in our private chat online. So clearly she got into my account and read my private chat with my friend not sure how she did that but being thats the only place the conversation took place I know thats where the information came from. Plus I asked her who I was talking to about and she said my friends name which the two of them have no clue each other are so I know its not remotely possible for my other friend to have told her. She tells me she didn't hack into my account that some guy she knows has some disk which I really dont believe. Reguardless the more I looked into it I noticed some of the stuff she was cursing me out in the text was things that were written in private emails on facebook so that means she likely went through and read all of my emails as well. The more people I talk to about this all tell me to press charges against her because she could of hacked into more than just facebook & could have my personal information and passwords for other things that are more important than just reading my private conversations on facebook. So im not sure what to do I obviously have her blocked on facebook and didn't intend to keep talking to her before all of this happened but now that we know she's clearly nuts for hacking into any of my private accounts im worried she would of hacked into my whole computer as well. Any suggestions?
Okay nobody special thanks for the answer but seriously with all the things im worried about I could care less if the way my question is typed out annoys you.