holding on last hope for a diagnosis

My husband and I have been separated for about 4 months now.  I am feeling so hopeless after 12 years of marriage.  We have struggled most of those years.  Since our separation, I have found information on adult ADHD and feel as though he could be a poster child for it.  I have asked him to make an appointment for an evaluation, which he did for next month.  I continue to feel disappointment and hopelessness as I continue to try to trust his word and feel let down each time.  He thinks that I only focus on the things he does wrong.  I just feel like I've ridden a roller coaster for 12 yrs and can't ride anymore.  We have 2 children and I hate that they have to go through this, but feel like I need to have things change for their sake at the same time.  I decided to look for a place where people might understand some of the issues I've been dealing with.  I just hope beyond hope that a diagnosis and treatment might make some changes that could make our married life bearable.  I am afraid of him going and the therapist not seeing the ADHD, although it is very obvious.  It is so scary and new to me.  We are also in the process of having my daughter evaluated.  She exhibits many symptoms.  I am thankful for finding this place where I can maybe get some support from others.