I think, if your mom isn't to old fashioned she'll eventually get over it. My own mother told me that when i turned 21 years old I could make decisions for my self. She has voiced some opinions on things I have done, but I always tell her what she said when I turned 21, I made decisions for myself and she can tell me she doesn't like my decisions but will respect the decisions That I made.
I think my mother knows a little about my crossdressing because I have left some clothing items (pantys, bras, hosery and some very definately womens tops) in her house that is now my house because she is in a assisted care living center, and I live there in the warmer months of the year.