My ex is going to hang with me this weekend...wat shud we do & is it okay to talk about the past?

my ex and I havent seen each other in 2 or 3 yrs We broke up because of lack of communication (i couldnt talk 2 boys on the fone and we neva saw eachother) Then a few months later i found out my best friend dat hooked us up went with him. I was more pissed with her cuz she KNEW how much i liked him, and did it anywayz. Hes a year younger than me, and i kinda used that as an excuse to not be so mad at him. I thought..we'll he's young...and she manipulative...which is both true...but neither is an excuse. though i should have been just as mad at him as i was as her, that was the past and i learned from it. Well recently we talked on mypsace, and we decided to chill this weekend. He may be coming over my house..im not sure yet. But is it okay to talk about the past? I mean i dont wanna sit up here nd act like it aint happen, but i dont want him to think im still dwelling on it either. Also what should we do if he comes over? Mind you im 15 going on 16 and hes only 15. So is OUT lol.