My experience with children (as somebody who is out) is that if they see other adults accept you and treat you normally, they will too. If you are still keeping it a secret from everyone else, they will be as embarrassed as you are when it is found out. You say that you have been "coming and going, dressed in whatever way that I wish". If this is the case, he and his parents already know and are all right about it. I say continue to do it, and show him that there are many options available to him as he grows up to be a man. By trying to hide it and acting ashamed of it, you are reinforcing all of straight society's oppressive prejudices.
