Goodbye..?

How do you tell someone that you need a break in your relationship?
That it's well as much them as it is you.
That you need space, and time, and solitude.
Tell them, you'll still be friends on Facebook,
but you won't see them for a while.
Won't text them, or receive text messages from them.
That you just want to be left alone.
For your sake. For your health.
How do you say "It's over. I can't take it anymore."
How to say "We can't be friends right now, and I can't promise we'll ever be again."
How to say goodbye when you still love them,
but you just can't have them in your life?

How do you tell a friend to leave your life,
that you want to leave theirs?
How do you?