Thank you so much for sharing your story U-Ming. I have no words to convey how awful that must have been, and even years now, the clarity you write about the event is telling of how impactful it was.
When you talk about your parents "preparing" you, it reminds me of how for many of us who identify as South East Asians, especially in a foreign country, the fear our loved ones have for us when we are treated as "other", stereotyped, sexualized, etc... just for being Asian.
It's funny, I will be moving to the UK for my Master's (also Oxbridge!), and when my parents found out my white, European, male friend was also going, they admitted they were relieved to know I would be going with a white person. It's telling of how deeply rooted foundations of white supremacy are in countries like the UK.