Need advice on custody/ ex issues?

My ex-boyfriend and I were together for seven years and had two children. The break-up was not a good one, but he was hard to deal with and mentally abusive. I took our two children and he moved about 200 miles away from us. He hasn't taken the break up well and he tries to use our children to control me. April 2010, he served me with court papers to get a paternity test and to enforce him paying child support. From April 2010 on, I have recieved threatening e-mails and phonecalls. We just went in to court on January 3rd 2011 and the judge granted him visitation for four hours every third Saturday. The Monday before he was to see the children, my ex-boyfriend called me repeatedly at work and on my cellphone, saying he was going to kill me, and that I would have to see him on Saturday and I couldn't use that b.s."I'm scared" excuse. I was at work while all of these phonecalls were going on. The next day I filed an emergency protective order so he couldn't harass and threaten me. He violated it two minutes after recieving it. I know the children love their father, and I was for the 4 hours of visitation, but I am afraid of what he will tell the children, I don't want them mentally abused as they are very young and impressionable. I was just hoping that there were parents who have gone through the same thing and could lend me some advice. We go back to court on Wednesday, and my stomach churns just thinking about having to be in the same room as him.