Just found out about how ADHD can affect our relationship

I have been together with my fiance for over 3 years now.  My fiance has ADHD and we both have known about it, but it has never been treated.  His parents never tried to treat it when the doctor diagnosed him as a child.  He told me from the beginning that he had ADHD, but I never thought that it could affect our life or relationship.  I found out last month that he was pursuing other women online and it frustrated me.  I felt so hurt and betrayed.  It started off as him looking at half naked women on facebook, then a secret world on twitter full of porn and conversations with these women.  I then found out a week after the twitter thing that he was looking at pictures of a girl he used to know in highschool revealing her breasts on facebook.  He was also reaching out to her by messaging her on fbook and gave her his number and said call or text me sometime.  After each incident I found out, I confronted him, he said he was sorry, and promised he wouldn't do it again.  He did this to me within a one month period.  Over and over again!  I have been in counseling trying to work through my issues and  we have never been to counseling together.  He has always had a low sex drive, and never seems interested in me or our sex life.  I have always felt that this was my fault, that I was never good enough for him.  He is also ignoring me and how I feel, he is content with the way things are.  He thrives at work, and thats about it.  He completely ignores me and his son.  He can throw himself into football, video games, online games, and things that interest him.  But when it comes to anything else in his life he falls short. 

He came across an article on the internet the other night that dealt with ADHD and how it can affect a marriage.  I really felt like the article hit home! I think he did too.  But he hasn't made an appt with a doctor yet.  Or tried to look into ADHD in adults and treatment plans.  I bought the book everyone else on here has and I feel like there is a little hope.  Even if me and him don't work out at least I know that I made the effort to try to understand ADHD and tried to help. 


It makes me feel better knowing I am not the only one out there dealing with this!