Guilt, guilt and more guilt

What a horrible morning I've had.
What a not-so-great summer I've had, so far.
I guess it begins with the kids I'm looking after. The dynamics of the group are such that there is an awful lot of fighting and arguing.
And it's wearing on me, day by day.
I don't know how much more I can take; something's gotta give, and soon.
I have five boys I look after, including my own. Who knew boys were such handfuls? There are two 7 year olds, one five, one four, and one just turned three. Aside from R (my angel, LOL) the other four are CONSTANTLY trying to "one-up" the others. I just don't get it. I guess it's a male thing, the whole "leader of the pack", "male dominance" BS. But it causes sooooooo much fighting. I can't take it anymore.
And as it turns out, neither can my own kids. At one point during the morning, R left the group to come into the kitchen with me (the others were outside) and said he didn't want to hear it anymore. I hear ya.
That was when I happened to witness another fight in the making. L was screaming at the four year old because he got to the swing first. Then he hauled off and punched him in the stomach!
I just couldn't believe my eyes. My kids are taught never to hit, or otherwise, and for most part they don't. L has his moments, with a swat here or there, but a full on sock to the gut?!
Being the red-head that I am, I immediately lost it - my temper that is.
That indiscretion just compounded on top of everything else that was getting on my nerves, and I completely lost my mind. I ran out the screen door, screaming at L to get inside, at which point I smacked him on the stomach (open handed though) to prove to him that it hurts. I also screamed at him at the top of my lungs; I'm sure the whole neighbourhood heard, the windows are open. I sent him up to his room and stayed in the kitchen, pacing, and literally shaking with anger.
And then it hit me.
I had done exactly what he had. I was no better than a five year old. I let all the day's (or week's) stress get to me, and I laid into him as I am not allowed to lay into the children that aren't mine. The ones that I truly want to lay into. Get it?
I feel horrible. I should be a better person that this. I just couldn't believe I had done that.
I dissolved into tears, trying not to get any in the KD I was mixing up. Then I went upstairs and apologized and cuddled with L for a while. And the look he gave me. It will haunt me forever. That trustful, sad look. The trust, that I didn't deserve.
Now I'm crying again. But I just feel so awful for doing that. Why do I let my temper get to me like that?
So now, I am trying something to hopefully help the situation from escalating again. I gave all the kids a stern talking-to at lunch. A whole big speach on being nice, not arguing, and following the rules. I also told them that I am implementing a new points system, where they will be losing points for arguing, and gaining ones for acts of kindness. The points will allow them to play video games, or not, if they don't have enough. I'm not quite sure how it's going to work out. These things always seem like a good idea at the time, but then end up being more work for me somehow. We'll see.
If this doesn't help though, I'm really afraid of my next step. I am going to have to "fire" someone. And I know who that someone is. I will have to admit failure, and just swallow my pride and tell his mother she has to find new care for him. I just can't continue to allow him to keep provoking me into this stressed out state. It's not fair, to me, or to my kids, or to the other kids either. And there doesn't seem to be a whole lot more I can do with him. I've looked after him for five long years now, and his behaviour has always been an issue. But timeouts are too juvenile for kids his age, and I am running out of ideas for punishments. I'm very limited with what I can do. So I'm praying, PRAYING, that the loss of video games will work with him.
Please let it work.