Hey, I talk a good talk!!! If I were in your shoes, a family feud would probably have already erupted. No one has ever accused me of keeping my mouth shut.
It really sounds like you are the whipping boy of the bunch and it has turned into a habit. Do they know how much their comments bother you? If they do, then they are just being downright mean. I don't mean to sound harsh and please don't take this the wrong way because I feel sorry for what you are having to put up with. But you know the old saying, "Put up or shut up" may hold true here. You may just have to have throw what we in the South call a "hissy fit" and put them in their place!!! .