Have first appointment with therapist this week! What to expect?

OK so a few weeks ago we discovered my husband of 5 years has ADD (maybe ADHD, I dunno).  It came as such a shock but it all made complete sense, every single one of our furstrations we saw was stemming from this.  Anyway, we finally made an appointment with a therapist who specializes in ADD.  I'm excited, but nervous.  My husband has been to therapy before for another issue years ago, but I've never done it before.  What can we expect the first time?  We are going together, but will they probably want to see him by himself as well?  I hear the first session can be really long, like 2 hours, true?  I just have this huge fear that he will be skeptical about it all and not accept the diagnosis and not want to try.  Mainly-he doesn't see how it's affected me all these years.  He sometimes laughs when I express my frustrations.  I assume that he may believe it more when coming from a therapist?  Please tell me there's hope that he will one day "see".  I have heard some of you with ADD say something similar to "the blanket has been lifted from my eyes and now I see what I've been doing to people".  I want that blanket to be removed from my husband so badly!  I don't know how realistic it is to assume it will ever happen.  Unfortunately we have to pay for these sessions out of pocket, so I don't know how we can afford many of them.  Do yall go every week?  Month?  Do you one day stop altogether if you feel you've gotten a good head start or is it an ongoing thing?  Sorry for all the questions, but this site is awesome, thanks guys.