My Fiance' was killed by a drunk driver do I have the right to sue this person?

Unfortunately, the fact that your marriage hadn't happened yet would almost certainly prevent you from bringing a wrongful death action.  I'm not a Maryland attorney, but my research suggests that the wrongful death statute in your state, like most others, only extends the right to relatives by blood or marriage.

I very much doubt that a court would make an exception.  A marriage, like a blood relationship, is a legal fact, but an engagement is not.