I'm friends on FB with my first HS GF. Nothing there at all, just old friends. She even came to our Christmas party this past December. She and the wife got along great.
My ex-wife did message me through FB a few years back. Boy, did I dodge a bullet with that one. Let's just say that she'd have to lose weight to see 240 lbs. But we're not friends on FB.
The girl I dated before my wife, (knew her in HS but never dated until after) and also prior to my ex-wife, lives nearby. See her around occasionally. Married, no kids, very nice person, we talk and there's no issue at all.
About the only one from HS I'd like to see isn't on FB, far as I can tell. Not friends with her brother, who I am friends with. I had my insurance with her Dad's agency for years, and he had pics of her and she was looking damn good still. Nothing there for me at all, just a person from my past that I wouldn't mind seeing.