As a mixed-race and ethnicity WOC, I sympathize. Personally, I believe that people who are Caucasian and 'other' are, at some level, always relegated to the nonwhite heap of 'inferiority.' I can look like a white person and have passed (though it isn't the norm for me), and there is absolutely no question in my mind that this is a huge advantage compared to not passing. As soon as they know that I am 'Arab,' though, which is only part of my ethnicity, I am automatically relegated the 'other' pile, and usually reminded of negative stereotypes.
As soon as people know the actual background, at some level, you are not white if you are 'contaminated' with other-than-white. That is, as soon as we acknowledge our reality, we lose this advantage. This hypodescence--which essentially guarantees that the dominant group stay small so as to have greater (of the stolen) resources for each--persists regardless.
It is great advantage to be able to pass as white. However, if we are not white inside, it constantly feels like a charade, as if our true selves are erased.
We are stuck in this liminal societal position as a result of white supremacy, which unlike any previous human system of human dominance has contaminated the entire planet. As a result, ALL POC are considered inferior even as we are not subject to the onerous anti-blackness that characterizes the core of white supremacy.
By the way, why wouldn't we be angry? The ones who aren't angry are worrisome: it takes a high degree of self-deception to not notice a heavy boot sitting directly on one's neck.