Mixing money and friendship, is the quickest way to lose both. It sounds like you two have been close friends for a very long time. I think you
both should just forget the BS (it's only $80 anyway) and work on rebuilding the friendship. In the future, just avoid any situations where you might end up owing one another for something. Seriously, it's not worth it, if you two were close for that long. Just my opinion. Carry on.