Who are you?

We talk once a week,
though we've never met.
I hope you don't get crazy,
Or come to break my neck.

We talk of our thoughts,
though you can't prove they are there.

You are a gentleman one moment,
and the next a joker.

I cannot read your mind,
Nor your face.
Are you playing me?
Trying to lose my good grace?

I'm getting a little scared.