It is okay to have a pity party now (and again and there is no better place to have it than this site); as long as you pull yourself out of it.
I too went through the anger and betrayal and the unfairness of all of this; and I will most likely have that anger again.
But I am now more focused on moving forward with my life and accepting that my (recovering) AH is going to do what he is going to do. I am still angry at myself for letting myself get in this position.
I just keep my eye on MY future and what I want that to look like, no matter what AH is or isn’t doing. What he does still impacts and hurts me but I just keep telling myself that I have no control over his actions just as he has no control over mine.
You are doing great and hugs to you.