I know you're nervous, but there has been a lot (and I mean *A LOT*) of research into the benefits of preschool. Look into what is called "The Perry Preschool Project"--a study done years ago about the life-long benefits of preschool. They are still interviewing the participants, who are now in their 40s. "The study found that adults at age 40 who had the preschool program had higher earnings, were more likely to hold a job, had committed fewer crimes, and were more likely to have graduated from high school than adults who did not have preschool." I'm just pointing this out to reassure you that it really is the best thing for him, even if it will be harder at first (for both of you).
Just something to think about.