Where is the "Thirdspace"?

I recently read a blog comment in which the author was explaining how, in her life as a white woman in a relationship with a black man and with biracial children, she felt as though she occupied a "thirdspace," different than just being regular old white. My first thought was, "Oh no you don't..." but the more I thought about it, the more this "thirdspace" seemed recognizable to me. I never think of my mother as the "typical white woman," because of the experiences she has had during her life, because she fell in love with a Middle Eastern immigrant when it would have been much easier for her to marry a nice white boy, because she raised three children amidst constant comments that we did not look like her and questions about where we were adopted from, because she learned recipes, traditions, words and phrases so that we would not grow up without our culture and because when people around her make false assertions about Arabs she has the strength to tell them that they are wrong. When you are white, perceived to be white, or just not black, you are privy to a lot of racist sentiment that is shared with you based on perceived racial solidarity, because white people feel comfortable saying things to other white people that they wouldn't say in front of non-white or black people (or you could be from Small Town, Midwest, USA like me, where many people are proud to be racist and speak openly and happily on it, no matter who's around). When in relationships with non-white people, white people (theoretically) are at once witnessing the language and the viewpoints of perpetrators in an exceptionally candid way, and witnessing the damaging effects of this racism and establishing a personal vested interest in those it hurts. This might be especially painful for someone who has never experienced racism (vs. someone who has experienced it all their life and is "used to" it) and didn't think about it pre-interracial relationship. But do I consider this experience something that warrants it's own "space," something that is entirely outside the white experience or something that overlaps with the experience of being of color? No, I don't think so. Because it is heavily influenced by the factor of being white, it is inherently within the "white experience," even as white interracial daters may be shunned from their communities.