I go by the ground rule of "if it was here before I." As in my smoking, I was doing it before my gf so she can't bark about it. This is way different.

I guess the main question is did he invite you to come along? If not why? Did they ever have a relationship? on & on

But here is the sad reality we have & we live w/...
If he would go to dinner & they end up falling for each other & he ends up leaving you, then that's the very sad reality we live. But if it could happen now it could happen in 10 or 20 yrs so might as well get it out now. It would bother me to now end but I would bite my tounge if my gf ws to go out w/ an old guy friend in fear of them falling. But in the same time if it happens it was bound to happen and now matter how hard it may be it would only be harder down the road. Plus, I do truely love my gf & know that I might not be "the best" for her. So, it would suck & f&ck me up for long time but I want her to be happy in life. I hold her above my own life so if that's what makes her happy then I would let her go.

I'm very sry you're dealing w/ this as even sitting here thinking about tthe siuation is now freaking me out!
I wish the best & what happens is what happens.