Hello. Robbie Rob, and welcome to the Grammar Exchange.
Since "don't attack me, please" is a complete sentence, when quoted in direct speech it should start with a capital letter, as all sentences do. Therefore, you should write:
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .