Why would you be annoyed with her mom giving her away? It may not be traditional but if that's what she's more comfortable with then that's the most important thing.
I didn't even want my parents siblings at my wedding, so wouldn't have even considered my grandparents siblings. They may be people my parents are close to, and they have always sent cards ect, but they aren't people I feel close to. And weddings are so expensive these days! You can be paying £50 or more for a meal for people, it's understandable that people choose those they feel closest to.
However, if your GD did say it would be better if you weren't there then that's very hurtful. Could it have perhaps been a response to you saying 'by the sound of things you would be happier if we stayed away' could she have thought you were being a bit childish and dramatic in that response (which it is a bit) so responded the same.
Is there a back story with you and her mom? Or her moms family? Or has her mom not been involved in her life? I don't really get why you would have felt that she didn't want you there just because she didn't want your sisters there (who are quite extended family to her) or because she chose to her mom to walk her down the aisle.