If you have thought it through, then follow this link to fully delete your Facebook account:
You need to go to the link using the web browser you use for Facebook AND be logged into Facebook at the time.
You can go the soft option of just deactivating your account if you prefer.
You may also want to download your Facebook data before you delete your account. Personally, I tried it and nothing useful or unique came up that I cared about.
So BOOM, I deleted.
Some things to consider:
1) Your account and data doesn't go away instantly. It can linger for months. So if you are cleaning up a a mess, then you should read this article and follow the steps before you delete your account. It will help you tidy up proactively as opposed to waiting for Facebook to sweep up months later.
2) If you delete your account it won't be "gone" for 30 days. So if you log back in, on any device, your account will be re-activated and the whole drama will just keep going. Make sure you delete all Facebook apps from all devices.
Good luck. Now go and enjoy your real life again :-)