Sounds like he may still want to be with you and yet he is not yet willing to give up the new girl just in case you say no, therefore, he will not be alone if he doesn't break up with the other girl.

IMO - I say walk as far away as you can until he decides what he really wants... and if that is you then his behavior will dictate that with his breaking up with the new girl so he can have you back in his heart.