If he is cheating, he is not very good at it. Most cheaters don't want to mention the other chick. So he is either falling for this other chick or he is doing his best to make you feel insecure. I would back off, and become too busy with something(s) to have time to see him. Let him be insecure for a change.
No he is being honest
I had a similar problem. I stopped paying him attention for a while and then he must have realised his petty little manipulation tactics weren't working the way he wanted them to. He called me, but I didn't ignore it, but it turned out he called me without anything in particular that he wanted to say to me, so we had a brief little conversation that was kinda awkward and full of silences, and then I said I had to go. Later on he started acting really nice and doing all this stuff for me. ofcourse there are girls who play games too, but that was just my situation. Just withdraw your attention when he starts yammering on about this girl. He'll stop when he realises he's not getting any attention. Oh yeah, and it's most likely he's just playing games, seeing how when you're cheating you actually knock yourself out to HIDE the other person.
Perhaps you need to ask him why he seems to be preoccupied with this girl, and then decide for yourself.
Not really how can he talk to you about you?
So sad...it means that he is an A hole
If he is not cheeting in person he is desireing to mentally. Weather he realizes it yet or not. Let him know how u feel + ask him what he thinks of said girl.
It sounds like he may be wanting you to act more like that person. Instead you are getting upset. <br />
I would tell him that you do not want to hear anything about this person again. Of coarse he may slip up once in a while but call him on this to reinforce your desire to not to hear this from him.