Infidelity and ADHD

I will try to be brief. My husband and I have been married for 10 fabulous years ( or so I thought). He is a strong, thoughtful, loving man, a wonderful husband and a great father to our two boys, 6 & 3. Which is why I was completely blown away when I discovered he had been having a sexual affair with my best friend and next door neighbor for 10 months. Yes, I sent him packing and we immediately started marriage counseling. Ou therapist diagnosed my husband with ADHD on their first visit together. It is just so hard for me to say that ADHD made him do it? He now tells me in counseling that he has always had low self esteem and never feels like he can do anything right. I never would have thought this about him as A. He has never mentioned, alluded, acted in any way that he has these negative feelings and B. He is the most cock-sure and confident man I have ever met, which is part of my attraction. I have read books on affairs and adult ADHD but can't find one on about those two subjects specifically. I am at a loss. So on top of dealing with the shock of his affair and the betrayal of my BF, the fact that her and I live literally next door, I now have to try to stroke his ego to make him feel better about himself? I am just so angry and I can't get away from reminders of the affair ( like seeing her or her kids or husband in the friggin back yard or at the bus stop) and I can't figure put how to deal. Tryi g not to lower his self esteem while discussing the affair is extremely difficult. Trying not to hurt him by expressing my anger is also hard. How do you Open the lines of communication to allow him to express how he feels about himself when all I want to do is say "this is your fault and you did it, I'm not gonna try to make you feel better about yourself" but in not so nice terms. Any thoughts? Anything? I am sure I left out tons of info but I didn't want to be to long winded. Thanks in advance