You don't really need to ejaculate....as much fun as it is.
Sperm die. Some of it is re-absorbed and re-used the rest is flushed out.
My understanding is some guys have "wet dreams" some guys don't. I, myself, have never had a wet dream and I was just as hot and bothered during puberty as all my friends, of which only a few ever admitted to having a wet dream.
Good luck on abstaining. You are a better man than I.