To root or not to root

So I recently started speaking to a guy I used to be intimate with over a year ago and he wants to do it again (Saturday which is 4 days away) BUT he has a girlfriend. She apparently cheated on him and their relationship is on the rocks and I just miss him and I don't know what to do; am I a bad person for wanting this? We were both still in high school and I don't know if it's worth all the drama going back to it :/ help