I never really thought about it, but I think I would want to call him by his name. I really don't know about the whole aap thing its sounds sooooo formal but that maybe due to the fact I wasn't grown up speaking Urdu. Even my parents call each other by thier names. I would think that when I get married I would talk to my husband in English, and probably use his name. Tum does translate to you in English and honestly I can totally imagine "you" coming out of my mouth easily......but I'm just like that :D I wouldn't be trying to be disrespectful.....I think it all depends on how you were grown up.
However you never know how things in life turn out, if aap or tum or whatever was the more appropriate way in his family, I would probably call him that (well at least in front of the in-laws)