Julie,
If your family thinks you're going to hell because you are ts then they probably have some very big problems in their own lives to deal with. Maybe knowing that will help you have a little more compassion for them (yes, it's hard to have compassion for people who are hurting or disrespecting you, but it's possible).
Let's be clear on two things: (1) nothing in the Bible condemns transexualism, and (2) as best as our present state of biological and medical knowledge can tell, transexualism is a completely natural condition -- i.e., it was created by God; we don't know why, but then we don't know why God does most of what God does.
All Christian condemnations of transexualism derive from supposed biblical injunctions against homosexuality. These injunctions are very dubious in the first place. But beyond that, transexualism, as we all know, is not homosexuality. A m2f transexual is not a man dressing as a woman, or a man who has a sexual preference for males. An m2f transexual is not a man at all. The old definition of an m2f as a "woman's soul in a man's body" seems fairly accurate.
Gaining acceptance by family members would have to be seen as a long term process. One part of this might be to engage them in discussion about the basis for their beliefs. Ask them, "why do you say I'm going to hell?" Ask them what passages in the Bible cause them to say this. Then, if you are motivated, examine these passages, and convince yourself that they do not in fact condemn transexualism. Even if you don't succeed in changing the opinions of your family members, you will be setting an example of keeping discussion at a rational and constructive level.
Cathy