I have no idea what your parents will think. None of us know them, so there is no way to say one way or the other.
However, think about the coming out process. It is your time to say exactly how things sit for you. I doubt if blurting out “I’m Trans!?!?” will get you to where you need to go.
Instead, think about explaining how you feel in very detailed terms. Is there an event that they know about where you can talk about how you felt or why you reacted the way you did? You have to “Command The Stage”, or also called “Hold The Narrative”. One way to maintain focus on what you are saying is to think very carefully about what you want to say. Perhaps you may make notes or write out what you want to say. But, I do not suggest that you just read what you want to say. It may lead people to thing that you are just spouting something that you read. The thing to do is put some serious and conscious thought into what you need to say. It is also a good idea to try to anticipate questions and be prepared for them. Once you have figured out what you want to say and how you will go about it, try it out on someone who is likely to be supportive. How things will turn out is directly proportional to the effort that you put in. In short, half-assed preparation will insure half-assed results.