I'm so sorry this is happening to you ,and I get it. I really do. I've spent my life encouraging my more timid friends to establish boundaries, and defend themselves from being taken advantage of because I've lived with anxiety about confrontations for a very long time (since I was a child).

So now, I'm encouraging you to master your fear and move past it, because I know its really hard. (I'm one of those people who simply bullies her anxiety!) The courage is not in the confrontation itself. The courage is in controlling and/or moving past the fear. Once you've done it one time, once you've set a boundary and successfully defended it, it gets a little bit easier each time ,and you will find that it was worth it, and that sometimes its okay to be just a little unkind.