If my parents held facts from me, I would see that as betrayal. I know it sounds harsh.

I don't think it is weird at all it bugs you, if you had a stable image of yourself (normal but maybe a little quirky?) and then suddenly you HAVE this thing... Somehow you have to react to this. Either you will let it change your image of self some, or you will decide the diagnosis has no say in who you are. Either way, i bet it will be on your mind a while.

Sooner or later you will probably again feel it is not a big deal but you have some processing to do before that.