[tallgreekalum]

The key question here is whether your school took action as well. If they did not, then you should be able to set up a local fraternity (using different name, ritual etc.) although some schools require NIC membership. After a number of years (ie, when any present Sigma Pis graduate), you would be free to affiliate with any NIC fraternity, if you so wished. Feel free to PM me if you want more advise)