The white is a minority thing. For most of North American post colonial history, white has been the best thing to be. Socially valued higher.
It's complete and total BS, bit you're going to have a very hard time getting that conditioning out of her head. Success is very unlikely.
Ditto the "straight." It's a cultural valuation thing, it's embedded in here understanding, it's because she loves you and wants the best for you, and it ain't gonna change.
Even though it's invalidating, sick, pathological, and frankly revolting.
Try to love her in spite of it, and don't you dare let yourself internalize it.
Basically, she probably can't change, but her opinions on the matter can go suck an egg. You are who you are, you are beautiful and delightful.
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"Alas, our dried voices when we whisper together are quiet and meaningless, as wind in dry grass, or rats' feet over broken glass in our dry cellar." --TS Eliot, "The Hollow Men"