What you are feeling is completely normal man. Trust me. I have been there. My ex and I divorced just over three years ago, and were also seperated. It killed me to see or hear of her with another man for a long time following the final signing.
The good news is that it does pass and there is life after divorce. It does take a while though. In the mean time, you have to find something else to do, think about, enjoy, and play, and move on... The last one may seem to be the hardest, but it is the most rewarding.
Somethings to think about in the mean time are.... how much contact do you really HAVE to have with your ex? With me it was much easier because she lived in a different state. She still tried to play the same games that your ex is now. When I would call to speak to my child she would drop little hints about how much happier that she is and all that. She even got my son to tell me that he was the luckiest kid in the world because he gets to have TWO daddies. Yeah, I know how you feel.
It took me a while to figure her game out, but when I did I found that I could force myself past it. When she would answer the phone, I would just say "HI, may I speak to... " at first she would try to be beligerant and drag my into a fight, but I was persistant, and didn't let it go there. After a couple months, it worked. She wouldn't even answer the phone. They had caller ID and she would just tell my child to answer the phone. :o)
SO, yeah man.. its normal. You haven't had time to get over the feelings and other stuff, so it only comes natural that you would want to beat the crap out of any man who is making time with the woman who use to share your hopes, dreams, and your bed.
Just get out of the house, into the gym, or whatever you like and keep breathing... there is life after divorce.
Keep posting here, there is a lot of healing in speaking with others.