Have a glass of wine or two with dinner. You'll feel more relaxed. Make sure your husband drives, or call a driver. BREATHE and have FUN!
It's good for your son, that you leave him once in a while. When I dropped my son off at preschool MONTHS after it started, since we started late, all of these kids were screaming and reaching through the gate for their moms. This was my son's first day and he looked confused and then looked back at me and said, "You ARE coming back to get me, right?" I laughed and said, "of course!" He then asked me why these kids were freaking out. I told that I had no idea. I raised my kids in a very secure environment and even took them to work with me the first year of life, but I always had other people holding them.
Make SURE you leave him more, even if it's for 2 hours to go shopping...just so it's easier for him AND you.