How to Cut off physical contact.

You cannot forget someone if you still see him or her all the time, or constantly hear about his or her activities. Consider these strategies:
Make sure you won't run into this person during your day-to-day activities. If you go grocery shopping at the same time, or take the same route home from work, tweak your schedule slightly so a chance meeting becomes more unlikely.
For right now, avoid social gatherings where you know he or she will be present. Politely explain to the host that you hope the event goes well, and that you are staying away only because you want to avoid a painful encounter.