ADHD & Affairs - redefining our boundaries

I'm working my way through the book, and am curious to hear what's working for other people. My partner has adhd, ocd and is on the autism spectrum - I am too young to be diagnosed with anything but am really trying to understand what boundaries I can have for myself, the relationship and how to cope   

With the stress of the pandemic, and our relationship maturing - I lost my partners hyper-focus in january and his ability to focus on me for sex diminished to the point where he was encouraging me to sleep with his (male) friend.  In October, the night before we moved into our first apartment, he slept with our (female) friend and neighbour despite me asking him not to - we are on the kink spectrum, but he lied to us both about it which is a huge violation of our negotiations around this sort of thing.  They accidentally slept together once before at a party years ago, and I'm still mortified he'd do this to me again.  I've since started working opposite shifts from him and they have a lot of time alone in the evenings, I trust that nothings continuing on however their friendship has elements I will request be changed when I move back to day shift.  He continually rejects me for sex, unless we've been hanging out with her, and so I chose to work instead of be faced with that pattern and his rejection.  We are working with a therapist, but have to space out appointments for affordability.  

target symptoms: distraction and impulsive decision making. 

If adhd is the explanation, and distraction is the symptom.  How do we maintain a monogamous relationship, without cheating, if there is a high to be had with other people?  He's had a chance to rebuild a friendship with her and has admitted to me that she has become his new high, and I am not willing to do a song and dance to compete with her and regain his attention after the affair that happened. He says it would never workout with her and he wants me, but more often than not I feel like he is refusing to manage his adhd symptoms and letting her become his new thing to hyper focus on.  

If adhd is the explanation, and possibly fear of failure the symptom - how do we correct the girl next door when she says he like a great dad to her son? Who's job should that be? Cause he might as well be given the timeline of their sexual relationship from years back (he is fixed and cannot be), and those comments serve as a painful reminder to me, I don't always feel it needs to be my job to correct and establish boundaries where he does not however will if it's appropriate to do so.  He hyper focuses on people and it's like all boundaries go out the window, one minute they're acquaintances and the next we're sharing old family secrets   

If adhd is the explanation, and distraction the symptom - how can we make sure the house gets taken care of before drinking and socializing with the neighbours?  I don’t want to feel like a parent or nag him but it bothers me when I arrive home after work (midnight) to him drunk or passed out and the house a mess - we've also been throwing food out because he eats with the neighbours so much

If adhd the explanation, and distraction the symptom, how can I not take it personally that he only seems to try to initiate sex after hanging out with the girl next door?  

For myself - If hopelessness is the effect, and fear of failure as well - how can I open myself up again to forming a sexual relationship with him again? It's been so fleeting since the affair, he rejects me constantly, now he wants it again but I'm afraid of my response when he stops trying again after he gets what he wants.  

I know some of this will have you thinking he's sleeping with her still, I trust her 120% that it's not that way.  There's more to this than I care to type out, these are the questions that have come up as I read the book - presently at step 4.  Letting go of the idea that I could control him has helped release the anger I felt at him ignoring my request not to sleep with her.  

He and I have rarely seen eye to eye on what healthy boundaries look like with others outside our relationship, particularly when he hyper focuses on them.  if it's not this girl, it's his family or his work that he lets into our relationships "house" to take centre stage and I lose all his focus and help with our daily life to whatever it is until they leave or cease to be.