Stand proud indeed. Either you're Dorothy or you're not. You can't have it both ways. If you don't stand proud, you run the risk of destroying your self image. You spent to many years in the closet to not go ahead and let them all know. I bet most of them already have heard about you and showing up in drab will make it look like you are ashamed of being who you are.

Yes, stand proud. Dress as feminine, girly-girl as you can. Act every bit the lady that you do at church. If anyone takes exception to you being you, then quietly apologize to your aunt for disrupting her dinner and leave with as much dignity as you can muster.

I assume your aunt already knows you as Dorothy, and is prepared for you, Dorothy, to show. She has probably prepared people for your debut; don't disappoint her. I'm betting that if you do as advised in the previous paragraph, your aunt will tell you to stay and ask those who take exception to either apologize or leave.

Either way, sooner or later each of those you are concerned about will have to come to grips with the fact that your are Dorothy now. Why not get it out of the way and get on with your life?