H1B,H4,140,485,.???Wojian,tks

Both my wife and I are h1b holders. And my wife applied I-140 and 485 last year, including me as a dependant. But 140 has not been approved yet. Now I am going to quit my job and start a small business. I don't know if I should change my status to H4 after I lose my H1b status. If I don't change to h4, am I in legal status as long as the 485 application is pending? What's my status in that case?

Thanks for you help.