You have every right to be upset. If there is anyone who should be patient and supportive it should be your parents. Your parents are acting like you're stuttering just to annoy them. I'd recommend family therapy or at least your own psychological therapy. Your dad, at some point in his life, will need your assistance and you'll not be able to be there for him since he’s not there for you now. I hope your parents see prepared financially for an assisted living since they'll probably not get your help. Is your father your natural father or a step-parent? Does your mother support your father or you? This is such a sad situation since you would do anything not to stutter.