Separation Anxiety

Any parents had to deal with separation anxiety? My son over 3 years old and starts school when he is 4. Right now twice a week for a half a day he goes to pre-school. And he cries and cries and cries when we are walking to school. He stops once I leave but I cringe as we walk each time. I just decided to pull him out of dance lessons because he was so upset in the class that sometimes he wouldn't even participate.

Any tips on getting him ready and used to being apart from me? I am a stay-at-home mom so he is with me when he is not at school.

Thanks, just knowing others have had it helps. We aren't abnormal