Co-worker unleashed

I have this coworker that reminds me of the movie "unleashed". I am very mild and passive. When I need some umph put into something I had a tendancy to go to this coworker for help. It was all hunky dory at first. CW (coworker) would call up company X and yell and demand management until something got done. This worked great when I knew we were in the right. The issue is CW's become a bit uncontrollable. I think CW is burning bridges with this company that we HAVE to work with. In addition, CW is turning his/her fury on other coworkers now. The worst part is CW doesn't bother to make sure CW is right before CW rips into someone. On top of that, if CW finds out CW was wrong CW never apologizes. I'm starting to feel bad for ever getting CW going. Anyone else have a loud-mouth coworker that flies off the handle? Any suggestions on dealing with him/her?