It's a slippery situation, dealing with your ex after a breakup. Whether you want him back for good, or are just trying to figure out how to proceed from where you are right now, how you two interact is very crucial...a sort of "make or break" point in your whole plan.
With all the emotion flaring up and feelings flying around, chances are good that there's already a substantial amount of conflict between you...prolongued contact with your ex will only lead to further agitation and things just getting worse. My advice is to try to reduce the amount of communication between you to as little as possible (taking into account situations that prevent total cut-offs from being plausible, such as kids or shared work/classes). Maintaining the proper distance will serve as damage control and help to provide a buffer between you and him that can save you from the dire consequences of spontaneous outbursts.
Another benefit to severing the ties between you and your ex is that you'll both have a little breathing room to get your acts together. Things tend to unhinge when it's all coming out at what looks like the end of the two of you...here's the chance for you both to reassemble yourselves and your lives. Sometimes a little thinking time and space to breath will be just what the doctor ordered...even if it's not enough to resolve your issues completely, you'll at least be in a better place from which to launch your plan to work things out.