You stood your ground so well. You can be short on explanations with Mom and Dad if you are sure it will just hurt them to try to explain. But you have said so much and gotten so far, and you are a non-baptized human being with valid thoughts. Tell them what you think you need to. And you have helped your siblings so well. They may come around and be your best friends as adults because of your honesty and willingness to say what you said.
I am also confident that your siblings have not looked anything JW up on the internet, but sooner or later they will.
It sounds like you are prepared well to proceed with whatever comes your way. But I tend to agree that it is already time to make progress with the non-JW relatives. Thanks for the update.