When should a lawyer disclose a possible conflict of interest?

A year into a lawsuit, my lawyer tells me that his wife (my lawyer’s wife) is a partner with opposing council. Interrogatories are over, depositions are over etc. I tried to find another lawyer but due to the amount of discovery completed, they don’t want to take my case (medical malpractice). Is this legal malpractice on the part of my lawyer? Opposing council has not changed. My lawyer knew all along that his wife was with their firm.