First Act of Agression :(

We had our first act of agression between Matthew and Julian tonight. Of course it was Matthew hurting Julian and I know it's only the first of many but OOOOOOOHHHHH how mad it made me. I had gone to the kitchen for something and left Julian on my bed and Matthew was there playing around him like he always does. All of the sudden I heard a cry come from Julian which was one that I've only heard when he's in severe pain (like his reflux pains that he used to have in the first few weeks which he doesn't get anymore thank goodness). I ran back to the bedroom and Matthew was there with the guiltiest look on his face. Julian was screaming/crying so hard that he was losing his breath and his face was beet red.  I asked him calmly if he hurt Julian and he told me yes. Then I asked him what he did and after asking several times he finally told me that he hit Julian with his own head really hard in the abdomen/groin area. I immediately took him to timeout but of course he fought me on it and tried to run away and it was hard for me to do much with Julian in my arms. After I calmed Julian down, I laid him on the bed again and went to the living room after Matthew. He tried and tried to get away and I told him that if he didn't go to timeout, he wouldn't watch any "bb's" (Disney videos on youtube) before we went to bed like I always let him do. He still said "no" and so I told him no bb's and then forced him into timeout. Aaaaahhhhh, what a night. Poor Julian. It made me so sad and I told Matthew that later. I said I didn't want anyone to hurt him OR Julian and that if someone hurt him, I would be just as mad. I explained that Julian was just a little baby and he was much bigger and stronger than him and he had to be careful. I think he'll think twice about hurting the baby but I know it'll happen again. It just will. I just hope I'm around every time to do what I can to protect the innocent baby who can't do anything to protect himself. Brothers will be brothers though and I know they'll hurt each other a lot when they get older too but at least then Julian can do more to defend himself.