It seems that you have made a major major turn in your path. You aren't looking at life through your AH's eyes anymore. And you aren't trying to understand, explain, rationalize, justify, or be accountable for his behavior.
As the good mom you are, you are focused on your son.
Soon, however, I think that your growing ability and willingness to let your husband just be who he is without a lot of engagement, will clear a huge amount of emotional space and time for you.
This may be the time to start thinking about what YOU want, just for you. Your son will be off to the next stage of his life in the next several years, and you are young with a whole future ahead of you, just for you.
I think this is a great gift you are giving yourself. It is your time to begin to imagine different ways you could live, play out different scenarios, and have fun with it.
ShootingStar1