Thanks to everyone who comment and/or left advice regarding O's separation issues. We left O with his Grandma on Thursday night and he cried for like two minutes. It's funny but it was his big sister who told their grandma just to leave him alone and he will get over it. Sure enough, he did.
So on Friday, armed with this information I presented it to the preschool teachers and when they were ready (i.e. done greeting the other children etc) I left O. I just went down the hall and waited to make sure he settled. He cried and screamed for ten minutes. Phew, so I finally left. He was perfectly fine when I picked him and was proud to tell his dad and his grandparents that he went to school without mom. Of course, we had a whole weekend in between the next class.
So this a.m., we did the same thing only this time he knew what was coming and was very clingy and held on to me for dear life. He finally let go and I left. This time, instead of turning right and heading down the hallway to wait, I decided to turn left and just exit the outside door and wait there. So I did. After a couple of minutes he stopped crying and so I left. Only this preschool has glass patio door facing the parking lot. Now he has never done this but when I was crossing to get to my van, I looked back and who's standing in the middle of the window looking out but O. CRAP. So I duck my head down and hurry to the van where I hop in and drop down. I peek over.. he's still looking the window. Double crap. So I hunker down with my cell phone in hand for a few minutes until I finally look up and see that he's gone. So I'm looking over making sure he's not going to see me leave when the teacher sees me and waves bye. Now I felt like a complete tool for two reasons.... a) Hopefully she doesn't think I was being completely dense sitting there where he could see me and b) I hope she didn't see me trying to flatten myself in my van like a twit.
Anyways, I'm hoping this will be the last day of this but we shall see. I appreciated hearing that this is normal for his age. It helps to know that even though it's driving me crazy. At least I feel loved. ;)