The affair thing is entwined through my sitch, so here's my thoughts...
IF there is a PA, try to figure out what and why...because it is a symptom of something that has nothing to do with you in all reality.
Pure speculation here...If I remember correctly, your H didn't get a job he REALLY wanted, that he set his heart (and ego) upon having...when he didn't get it, as a man, he might have taken a huge blow to his sense of worth, and therefore self, as many men tie their self-esteem into their job, income, provider status and so forth. Maybe this was the trigger that set off mlc, who knows. So, he pulls away from you because sub-consciously, he does not feel worthy of you (and the difficulty in having kids probably plays in here somewhere too). This running away from his bad feelings about himself (blamed on you because it is so much easier to find an external cause for our discomfort) then has him searching for self and self-esteem, since not getting that job threw all that on the rocks, leading to doing all the standard mlc stuff...including EA/PA possibly.
So, before deciding IF you can forgive and trust again, maybe try to figure out WHY the POSSIBLE affair happened/is happening...
For my W, and I am on the second round of this, it was a mixture of unresolved things from the past, and...PROVING HER DESIRABILITY the first round...this round is proving desirability again and also mix in some replay/exploration from teenage/young adult "wild times" she never had due to her past and low self-esteem and a fear of getting old, she played in cougarville.
As Jack said, if you can/want to forgive, you will. For me, figuring the "why" helped/helps me to truly forgive, and actually, the EA aspects hurt more than the PA aspects...but remember, it's not really about you, its a symptom of mlc and H's attempts, although a very poor way of going about it, to ease something painful in HIM (such as proving his self-worth as a man).
For me, true understanding lead to compassion, which led to forgiveness of a real, true nature...
The trust thing will take time, and him proving to you, and also you allowing him to prove himself...by giving trust forward...by choosing to trust, even if you are not sure...and giving yourself the benefit of the doubt as well...
But, that is for later, not now. Now is for finding understanding.
You were just waiting for some new wrinkle to figure out, weren't you? Like we all need some new mlc weirdness to untangle, huh...lol...
Hope this helps...YMMV
T^2
In the depths of winter, I finally learned that within me there lay an invincible summer. - Albert Camus
Uncertainty is the very condition which impels people to unfold their powers.-Eric Fromm
