I actually tried reconnecting with a former friend from 20 years ago. She lives a long way away now, and I thought, like you, what could go wrong by just chatting?
It didn't end well. Don't feel like going into detail for my own mental healths sake, but I feel like giving you a warning anyway.
Long story short: it took me less than 24 h to remember why I cut her out of my life in the first place.