I get it. My dad said I had been lying to him because I didn't tell him when I first came out. I explained that I wasn't lying, I just didn't feel comfortable talking about such a personal issue.
You have never lied about it. You are undecided because you are still learning what all of this means and whether or not it applies to you. Maybe it does. Maybe it doesn't. Gender is not cut and dried this or that. It is a spectrum and many people, even here at Susan's flow back and forth along that spectrum. It is not right or wrong.
I would strongly suggest you seek out a therapist or psychologist with experience in gender identity. They can explain things to you and help you figure out what is going on. You may be something you hadn't considered. It is not either/or. You could even be gender fluid. Some days you feel one way, the next day something else, maybe even some days both or nothing.
The important thing is that you are not lying, to yourself or anyone else. It isn't a matter of changing your mind. Maybe that is how you felt at that time. Maybe you feel differently tomorrow. It is all perfectly normal.
Just remember that people who do not experience the things we do have a very hard time understanding what we go through. They can still love us and support us, but maybe just don't really understand. That is ok. Because as you learn, you start to understand, then you can help them understand. Some will not be interested in trying. Some will be supportive, and some won't. You are not responsible for how they think or feel. That is their issue to address. All you can do is be true to yourself and let others see that you are just being you.