ADHD in both partners one undiagnosed

Hi everyone hope this is the right place. I'm looking for some help. My marriage is at breaking point at this moment in time. When I first meet my partner she had undiagnosed ADHD and her son also ( he was 3 at the time ) . Jump a few years ahead and they were both diagnosed with combined ADHD. We now have a child together now so their are 4 of us. 
 

Last week my wife wanted to talk and said that she wanted to separate because she was fantasising about someone she see on our holiday in September and she said it didn't feel right being together at this moment in time. She said she didn't know if it was something she wanted or a phase of her ADHD that she had previously had in the past. She said she has masterbated over him 3 times since we have been back. Once as soon as we arrived home which she thought nothing off it. Then twice just over a week ago. She didn't want to keep it from me that's why she told me so she could try and figure this out.
 

For the past 5 years I have struggled with her son ( my none biological son ) and he's ADHD. She has nagged me over the years to sort myself out and give him the care that he needs. I would be ok for a few weeks then would go back to normal telling him off and not giving him the proper care a child with ADHD needed and treated him like a child without ADHD as I have 3 other children from a previous relationship.


The last two days I have listen to both of Melissa's books. I can resonate with nearly everything in the books to my wife parenting me etc and one story that upset me so much because it describe everything my wife has said to me about the way I have been by not doing as much housework etc and pulling my weigh and leaving her to deal with everything. I believe that I too may have ADHD but only the inattentive type. But listening to these has made me realise that I now at 36 know myself. Because Iv just been plodding through life and accepting everyday for what it is.
 

When speaking to my wife about it she just says you probably don't have it you just show some symptoms and seems annoyed that I'm hyperfocusing on the issue. 


I don't know what to do to try and save my marriage because it seems that I'm trying and after a week my wife is getting cross and annoyed at me for trying to talk to her about it. Which I though she would of been caring and helpful over this but she has been the opposite.