If you think that I should tell him, should I wait until he's over her?

yes i would tell him you like him more then a friend and see what he said to you i would want to tell him to his face to see the look on his face but if you talk on the phone or he is emailing you and he talks about his ex or something like that then i would tell him then that you like him more then a friend ask if yous can go out one time well good luck