I'm a s*cky parent

My 3yo has had a hard time at preschool. It took 2 weeks to get him to go in without prying him off my leg. Today I got a call that he had pushed and bitten another child. He has never bitten anyone at home, so why does he pick someone else's kid to start with, grrr. I went to school, gave him the firm mom talk and told him his beyblades would be gone until he could act better. Dh went to pick him up 30 min later and he had scratched someone since I had come home. Double grrrr. They are giving him Thursday as a final chance and then he's kicked out of preschool. There isn't a big enough rock to crawl under. I can here the locals now "If she didn't have so many kids she could control them." and other variations on that theme. Dh went bonkers. He is so mad he can't think straight. I feel bad for the other kids and am just plain old embarrassed and am wondering why my kid can't just be good. Typical of mothers I'm sure this must be something I've done wrong. I realize I didn't do the biting but that doesnt' change the way I feel. Ok, I know in 20 years it won't be a big deal but... sigh....