I don't think transitioning was scary for me, it was more welcoming. Fear of parents I never overcame, I grew up, left home, grew old. Their opinions no longer mattered. I still never told them, the newspaper did that for me, that and my sisters. Life wasn't kind for me back then and growing away was the only way.
For you, it would be helpful if you had an ally in your corner as without at least one, life can turn hellish quickly. Talk to a school counselor or a therapist before talking to your parents. Prepare information resources for them, a few websites and a book or pamphlet for them to read and ponder. Be prepared to answer questions and remain calm no matter what the reaction.