Why am I such a kid?

I'm angry at myself. I do VERY stupid things. Childish and unwarranted. I am better than this. I know that I am but I can't seem to help myself sometimes. I'll be going along just fine and then BAM! I have to do something stupid. Today, I sent out the confessionary mail to my friends just like a play around thing that someone sent me and so I forwarded. It's confessing stuff that I have done while in a relationship or what I really thought about someone I was in a relationship with. One part of the mail was about Mysterious Ex, it's very mean and not very nice at all but hey, it's the truth right? So, I cannot be satisfied with just writing it and sending it to my friends, no, not crazy me, I have to send it to him to. To seem as though I "accidentally" sent it. I mentioned that fact that I'm expecting too. Why do I do this? There is really no reason at all that I should send this, it's just to hurt his feelings and make him feel bad, that's very childish and quite unecesarry. But, I did it anyway. One part of me says fuck it, he's hurt you why can't you do the same? The other part of me knows it isn't right. But the real question is, do I really even care? It's just so stupid.