Depends what he represented you for and what he may have learned that could be used against you now. I wouldn't do it just because of the appearance of it.
I agree with Mr. Thompson's response. Without knowing what specifically your future former father-in-law represented you on, the existence of an actual conflict of interest can not be assessed. On a personal basis, I would avoid such representation under any circumstance with the possible exception of a divorce and custody situation in which both parties on firmly on the same page. My suggestion is that you focus on your representation rather than your spouse's. If the nature of the prior representation is such that an actual conflict exists, your attorney with you can determine how to handle that issue most effectively.
Sign up to receive a 10-part series of useful information and legal advice about the divorce process.