Suspected cheating

My husband and I are both ADHD diagnosed and treated. He has much more severe symptoms than I do that are moderately helped by high doses of Ritalin, except when he forgets. I do pretty well on adderrall- keeps me calm and not as spacey as without it.

I don't know what to do as my husband of many years says he wants to stay together, but does not seem able to be emotionally intimate with me, lost interest physically a few years ago (suddenly less sex and trouble with erection), and seems to continually need time away from me in all sorts of public situations. Recently I have overheard him speaking in low romantic tones on the phone and even saying things in his sleep he doesn't say to me.

Since 3 years ago, I have talked about divorce 3 times. Each time he suddenly behaved more attentive, begs me not to leave and convinces me, but then goes back to the same inattentive behavior.

My husband is super smart (and grandiose). I don't think I will be able to catch him in his infidelity and he insists he would never do that. But almost every day he says or does something and acts irritated and won't answer questions and if he complies with a request from me it is begrudgingly and sometimes with anger. I just think if he was faithful and happy in our marriage he would be consistently treating me as someone special to him. He used to, but not anymore.

What do you think? I feel like I'm going crazy and/or I'm a bad person for wanting more. We raised a large family, a few kids hardly talk to him. They usually prefer to see me without him. He has a large family, however, that I'm afraid to offend, because they are pretty good people though his dad is divorcing his 3 rd wife.

there has been porn and the erratic behavior makes me wonder if he is seeing sex workers and not actual "girlfriends".

I will appreciate any questions, perspectives and