Fuel in diesel

I filled diesel truck with unleaded. My husband is not happy with me. He screamed and went to bed. I filled it, turned it on and drove a mile before it stopped. Then I got under the hood and pressed this metal round thing until it became hard to push. (Husband had told me to do this in case the engine did not start). It started but promptly shut off! Is there any hope?? 2008 Chevy s10.