Do I have a chance fighting this citation?

1:00am, I pull out into the highway with my husband and 3 kids in our Subaru impreza hatchback. I see a highway patrolman has pulled out behind me. I am very aware and cautious of my speed. As I begin to accelerate, the officer comes up behind me very quickly. He is so close to my bumper that my husband says, "pull over, let him go around". I do, the officer backs off, I scoot back into my lane, his lights come on. He gives me a warning for driving on an improved shoulder while prohibited. I even told him he scared me coming up so quickly behind me and he said 1) He had to get that close to read my license plate. 2) I should've used my blinker to scoot over. Is that true? You have to use your blinker while allowing someone to pass? And if not, if the reason he pulled me over was unlawful, then will the preceeding citation (for something different) hold up? Or can I fight it?