Well, I truly admire your concern for your grandson's well being and emotional health. This is a tough situation for sure. But, I feel that if your Grandson has a possible interest in heels, he will discover them sooner or later, even without knowing you enjoy wearing them. So, perhaps it is better to talk with him now, kind of "feel him out" on his opinion of you wearing heels. It surely sounds like your Grandson has been raised correctly and would accept your heeling fully, even if he is not interested in wearing them. But, in case he is/might be interested in wearing heels, perhaps you can help him by exposing him to your heels now, so this will help him to feel that it is "OK", and he will be accepted and encouraged by family members. I spent so many years trying to "hide from myself", crippling myself with self hatred, I just hope I meet a young guy someday that I can help avoid wasting so many valuable years.
You are not exposing your Grandson to anything "bad", you would not be giving him his first cigarette or beer. I know that you only want the best for him though, and I respect you greatly for that....Don