Right.
Intuition alone tells me that guy 1, however nice he may seem, is the one lying in all of this and he is just taking route 2 (the easier one I suppose) of just denial and reassurance to you. Guy 2, because of the potential other girl thing going on there (though that may have been guy 1s defense mechanism) seems a bit too dodgy to both yourself with if im being honest.
Guy 3 seems to be the only one whose truthful, or at least not suspected in this situation. So I would just stay friends with guy 3, if thats all you want there... and maybe just try and be less effected by 1 and 2, because they dont seem 100% honest, really.