Therapy is a good thing, especially for dealing with things like, well, how to handle your family situation. If you're in college, you might have some access to counseling services that could help you out; you might want to seek out the advice of other transgendered college students to find out what the best options are. Coming out to parents is probably the hardest part of coming out. It's a lot easier to come out to close friends, and they could give you support for dealing with your parents. If you are really afraid of a very negative response from them and you depend on them, perhaps you can wait until you can become more independent (financially, socially, etc.). But when to come out, especially to parents, is a very difficult and personal decision, and i couldn't hope to tell you when is best.
Best wishes,
~Alyssa