“How do I choose not to share my account information with Facebook?”
Or... you know... just use something like Telegram that isn't owned by Facebook.  Their data-sharing / privacy policy is pretty simple <a href="https://telegram.org/privacy" rel="nofollow">https://telegram.org/privacy</a><p><i>1. Sharing data</i><p><i>We never share your data with anyone. No.</i>