I have been following this, mostly via Jen Lancaster on facebook. Have you read her books? She's a big girl and has the BEST attitude about, "whatever, I have totally just as much right to be here on this beach as you do and I have it going ON" I have ever read. I LOVE her. Even some of the things I don't like, I can overlook because she's got such a great attitude about being a big girl. Even the book she wrote about "dieting" was so grounded positive. She is an excellent counter point to all this madness. Look her up!
Her blog is http://www.jennsylvania.com/
I disagree with her on a lot of issues, but on this she is a great role model for women who might want to lose weight but also want to love who they are right now.
Your costume sounds AWESOME. Go and have a good time. If you let jerks like Maura Kelly change how you think and live, they win.