(F)inding out that (m)y ex and I have developed the same fantasy

So about a month ago I found out that a girl named Alex who I had dated in high school (and hadn't really spoken to since) had transferred to my college. I decided that what was in the past would be forgotten and texted her to see if she was up to hang out at some point. She replied really quickly and enthusiastically so I figured immediately that she was interested in reconnecting. I invited her to a party that weekend and waited impatiently to see her again.