What message is being sent?

He chose her over you & that's the bottom line. He would have walked away from his relationship in a heartbeat if he was in love with you but he wasn't . . . he was having sex with you & cheating on his (then) girlfriend. I don't see any harm in meeting an old friend for lunch (my best friend is male & we've been friends for 25 yrs) but I don't think you should have any great expectations about it. He's probably being nice to you during a difficult time & extending an offer to meet a good friend who might need to talk. It's not like he's on you every second texting about when you're going to meet. I think you should let it go considering your feelings. He already chose her over you once before & most likely will again. Sorry :-(