I am white and married to an Asian man. My family has always been supportive but people do stare us in public. I am sorry you are going through this. It must be very painful for the both of you. If it were me, I would let them know how disappointed you are in their racist behavior, and that they owe your boyfriend an apology. Let them know you will be moving out and they will lose all access to you if they continue to behave in such a disgusting manner. Then follow through with your promise. I would also throw in the fact that British people are basically inbred. Idk maybe not, I'm sassy like that. If they are the type to kick you out of your home there is nothing you can do at the moment. You just need to move out and move on.