That's my boy! The one beating up your kid...

So last night we got a very upsetting note home from my sons daycare.
My son. The little boy who is 3.5 years old. The one I love more then anything is... A bully!
The note did not say he was a bully, it did say he was beating up other kids at daycare, and unfortunately in the 3 months he's been there, it's the 2nd time we've gotten a note like this back.
This absolutely kills me! How can my son be a bully? After years of being bullied myself, I somehow am raising a bully?
So the first question, how do I explain to a 3.5 year old why this is bad?
Well, if there is one thing known by anyone who has ever met my son, he is a Momma's boy! He wants me around 24/7, he loves me more then he loves anyone else. When he is hurt, upset, sick, or even just wants to play, I am the one he wants next to him. Something I love, and try to discourage at the same time. Quite frankly I don't want him to be a 30 year old man that comes running to him Mommy every time someone upsets him. I want him to be a successful and capable adult. I deal with mommas boys at work everyday. It's not good.
So we had a chat. And I explained to him that when Mommy was a little girl people used to hit her and yell at her the same way he is doing to the kids at daycare. It made her very sad and she used to cry. Now finding out that he is doing that to other kids makes me very sad and want to cry.
He wrapped his arms around my neck and said "I'm really sorry Mommy."
So I thought, great, made a little headway.
Then moments later he kicked me when he got mad I wasn't feeding him candy for supper.
Hmmmmm...
May have to approach this differently...
So after he fought and refused to do his chores, which involves keeping his room and play area clean, and spent the night yelling at his father and I because we wouldn't let him watch cartoons, we fought with him for 30 minutes to get him to go to bed.
So... Some new rules are being implemented in my house.
Basically, at home we let things with him slide because we feel it's harmless. However perhaps us letting it slide is making him feel entitled around the kids at daycare.
We're taking a really hard look at ourselves, and although we feel that overall we're pretty good parents, we may be too relaxed in some of our rules.
So here it goes. I'll let you know how things are progressing in the future.