wow, what a night

Some thing happened tonight and I'm really upset. Bed times are a struggle for Zach. He doesn't want to go to bed, so we let him stay up. He's usually good and will watch a show or play a computer game. Lately, he's just been a big brat and is totally hyper and when we tell him it's time for bed, things get ugly. At about 9:45 (it's now 10:30), I told Zach a story and told him if he went out of his room, he would get his pup-pup taken away. Alan came in and said good night to him and Zach just starting throwing a fit. He was yelling. And when I say yelling, I mean "yelling so loud it hurts your ears and makes your blood boil" yelling. I told Alan to ignore it because he just wants the attention. It got worse. and even worse. I couldn't take it any more. Now, usually when he acts like this, I can't handle it...it frustrates me and I want to smack him. But I was calm. I took him out of his room and sat him in time out. I got a chair and sat right in front of him and loud enough that he could hear my over his fit, I told him how rude and disrespectful he was being to Alan and I. I told him it is NOT okay for him to act like that and he will not ever get anything he wants by acting that way. He calmed down a bit and said "but I wanted some one to give me covers". Again, I told him he will not ever get anything when he throws a fit like that. I explained that if he wanted something, he needed to ask nicely. And if we decided to say no, he could be upset, but it is NOT alright for him to scream the way he did. Anyways, so, I told him that he was not leaving that chair until he calmed down and told Alan and I that he was sorry. During that time, something happened. Zach looked into my eyes and we stared at each other for about 30 seconds, and in that time I saw this bratty little boy, as a sweet innocent child who was acting the way he was taught. I have taught him to behave the way he was. When I get upset, I lose my temper and I yell at the kids. Today Zach yelled and he was put in time out. He yelled again, and I smacked his mouth. He kept saying "mommy, be nice to me......." At the moment, I was so upset, I just thought that he is in time out, I'm not being mean, he's just being a brat. But there is nothing like your little child saying "I want you to be nice to us" to make you feel like a shitty mom. really. I hate when I see these moms who are just so great at it. They love spending time with their kids and love being a mom. I really don't enjoy it all that much. But who's fault is that? mine. I have these two sweet kids, who have a crappy mom and I'm not sure I'll ever be a good mom. Anyways, just have a night.......not feeling sorry for myself like I normally would in a situation like this. I'm just really feeling like there needs to be a major change, but I'm not sure how to do that.