Annulment or divorce?

What is the name of your state? MA
Which is more quicker an annulment or divorce in Boston?My fiance' found out that the woman he helped support financially way back in 1998 filed for a marriage certificate and now we can't get married because of that woman. My fiance was not aware that he is already married to that woman and they are not living together. What is the best action that we are going to do, the best and quicker way?

thanks a lot!!!

We need more information.
There is no common law marriage in MA, how is she claiming she is married?
Was there a license? Were they in another state like PA which does recognize common law marriages?