Learning opportunites come in strange shapes and forms. In your shoes (I wish) I would turn to humor. When someone throws you a challenge about your age, run with it. "Yeah, due to the nursing shortage they're now giving candy stripers nursing licenses! A little poke here. # tubes of blood and you're out of here.
I'm over 6 feet tall, male. I went into the lobby looking for a patient. As I passed one of the street people waiting he loudly said "everyone knows all the male nurses here are gay." I replied just as loud "that's true! And yet, here you are."
This will get easier for you with experience. If you're losing sleep or having nightmares it may be time for a job change. No job is worth that. You didn't get this far without being strong. You can let people put weight on your shoulders, or you can find another way to handle it. After all you are a fully competent nurse, and that doesn't change because some people are rude. Find ways to manage it. In nursing like in life, there's always a new challenge. Challenges seem really huge till you come up with a solution, then they seem so small. Wishing you a long happy career. Paul.