You have my commiseration and compassion. There are mean people everywhere, fortunately the number of good people far surpasses those with evil thoughts.
Most all of Facebook accounts are secured. When accounts get compromised it's usually due to neglect on the part of the account owner.
Protect your password:
Don't use your Facebook password anywhere else online.
Never share your password. You should be the only one who knows it.
Avoid including your name or common words. Your password should be difficult to guess.
Use Facebook's extra security features.
Make sure your email account(s) are secure.
Log out of Facebook when you use a computer you share with other people. If you forget, you can log out remotely.
Run anti-virus software on your computer:
Think before you click or download anything.