Divorce Support Forums: Grounds for Annulment

Me and my stbx separated about 5 months ago and there is not possibility of a reconciliation. I live in the state of Maryland and wanted to see if I can get any information regarding possible grounds for annulment. I know that fraud can be used for grounds but what constitutes as fraud? Would my stbx saying he wasn't ready to get married in the first place be an indication that the marriage should of never happened? Also, his mother told me after we separated that her son came to her three weeks before the wedding not wanting to get married (it would of been really nice to of known this before I walked down the aisle) I would be appreciative of any type of information or knowledge you have about the annulment process in general. I have a lawyer but figured I would get all of my ducks in a row and ask differing opinions before I go to her.