Confused

Ok, so I thought that my mind was made up on my work situation, but now, my big boss Jason threw a wrench. He heard I was leaving, and was willing to go to bat for me to the CEO. He wants me to stay on at Cellular One part time and match my pay. Now im so confused. Is it ethical to accept a job then turn around and tell them I can't take it?? What do I do!?!?