Massive bill for antidepressants gene test??

My dr suggested I take a gene test since no antidepressants i’ve taken have seemed to work. I asked about the cost, and she said around 300 if insurance covers it. I don’t remember signing anything that said i’d pay the amount if insurance was denied. I assumed i’d get a warning if my insurance was denied. Apparently my insurance was fucking denied because I was just billed 5500. Someone please tell me what I can do? Is there any way to dispute the charge? No one told me it would be that expensive. I feel stupid because I should’ve grilled for a more clear answer but also feel mislead. I never in my mind thought it would be that much. Ironically if I didn’t have depression before, I DEFINITELY have it now. Someone please help. Im about to have a mental breakdown.

Edit: Also, my results were, “Seems that all medications interact well with you! Good news!”