I know of what you speak and think. I live this every day and every night of my life. I know it sounds suicidal but is nothing I would act on, but I'm searching for reasons to face each new day that won't stop coming and looking for the good that's left in life among the rubble left behind by STBXH.
For an entire year of my life (2012) I fought a raging battle for my M and I too was a SAHM for the last 12 years. My heart and soul were M and him and DD and he knew it. I used to tell him how much pride I had in us and being M to him and being part of his life and family. I told him constantly.
I did not know that I was working against invisible demons and feel so angry that OW knew of me but I did not know of her or the real reasons for changes in his behavior.
I, too, struggle with the A but find I speak of it aloud less and less, because I get yelled at and lectured about how destructive it is for me to think.
All that said, I will offer some advice my counselor gave me for when it becomes consuming. This counselor has given me some of the first glimpses of validation since abandonment and first dday.
Her words are: "let it come. Your brain is seeking ways to process events and ideas that occurred without your knowledge. Know that you have this knowledge, your brain is in such shock and turmoil that it has to focus to an extent on the A."
She said further that there is nothing wrong with thought processing the A or people in it, it's how we behave or what we do when those thoughts and emotions come. I'm really glad you're questioning contacting your WH with what you know, because I think you may know deep down that it's not a good idea.
If I attempted to ask or discuss OW, STBXH got red-faced and like a kid having a fit. Even though it tortures me, I finally understand that it's actually me causing myself more damage when I contact him for any reason, but esp. that or about her.
I am searching for another place to channel those thoughts and that energy. One way I do that is to be on SI and try to give any advice I can to others who are in earlier stages than I am. If there are ways you can work on it without involving your WH in any way, my counselor said that's a really good thing. It allows yourself to have to process and deal with it, but the destructive parts are taken away by not contacting the actual people.
Journals for this don't help me right now but places like this do, or a person I can ask a question about it helps the very most. I only have two people in my life who don't lecture me and who will discuss it freely-a cousin and the counselor and they don't have anything to do with him. So one suggestion I would offer is to see if you can find a confidant.
I'm getting long but wanted to touch on the "being strong outwardly" comment. I find this impossible most days and have finally said to people, "I will get in touch with you on a stronger day". If I am too down, I put up some boundaries and that way save berrating myself for being lousy company. I also just tell our daughter when I am down and generically why, so she can know it wasn't her actions or words causing my melancholy. Especially because of her age-10.5-I don't hide my feelings because I want to figure out to be open with her when teen years come. Most adults we know aren't real with feelings with her and I think there is a way to be, so I do it simply.
STBXH grew up hiding his feelings and truest needs and finally burst wide open like a bean bag. I don't want that for DD or me but I know that it was his own choice to hide his needs from his wife and family. I was here waiting to work with him, while he was off spewing to OW and others.
Sorry for my long letter but to repeat, I do think you are wise to simply go about info. collecting and keep it for a day that will surely come when you can tell him what you know. For certain, I've felt that and in the heat of emotion have brought it up to Perv and been bitten, making it worse.
There's another little piece before I end that I've heard from local people who are BS also. They have discovered that oftentimes, showing something you know about an OW or OM says to the BS that you are interested in what they're doing and that fuels the ego more and there've been OW/OM who actually gloat behind the back of the BS. Then they toss it in their face in court or in front of friends or kids and it really gets ugly.
The high road is deserted, dry and long, but is a source of pride for me during a time when there are so few sources of that.
I too have worked every day and am detatching from the M. Perv I am no longer attracted to and find him disgusting because of his actions, but yes, the M was my life too. My sense of family is destroyed and so I am trying to focus on creating a new sense of family for DD and our baby to be. It's less draining but hard to hear the advice "focus on your children". It really does work but when our hearts and minds are disconnected is very hard to hear and then do.
There's also a good thread on SI about acceptance and once I have been able to do that, I can be calmer in my mind and heart. It's not to say happy, but other realizations are able to work their way into my head.
I wish you well and a glimpse of peace and sunshine in the rain.
A person is a person, no matter how small. -Dr. Suess
Perserverance and spirit have done wonders in all ages.