Since you're under 18 I can't tell you to get as far away from your toxic mother as you can, though I'd like to and I'm very sorry you have to deal with such invasions of your privacy. You need to keep your private diary and messages away from your mother. Switch to keeping your diary on a private, password-protected blog. Always delete your browsing history and cookies after visiting to make sure no one can find out about it. Create a new email account your mother doesn't know about, and again delete all record of it after each visit. If you have your own computer, boot password it so no one else can access it (typical account passwords are useless--any idiot can bypass them).