Not sure that "getting out" the issues you have with him (A, lies, spending, secret life) will get you anywhere, especially in terms of "letting go". There is a point in time where you know you have "aired" everything, and you know what, most often times they don't give a rip. At some point, you will truly just "let go" and try to forget about all of the CRAP (nice word). It happened, it's over, it lead you to where you are now. Does it matter? To you yes, to him no (more than likely). Airing this stuff isn't going to get him on a better track, a track where he can be a solid parent, anytime sooner. As a matter of fact, he very well might be tired of hearing about all of the mistakes he made and the sooner people quit reminding him about them the sooner he too will be able to move on and quit feeling like a loser.
I'm not saying that you should really cut him any slack for HIS good, I'm talking about for the sake of the kids. I know when my moment of epiphany occurred, the moment I decided to quit pointing out all of my X's mistakes. It was after the divorce and was either July or October, because we were eating out as a family for a birthday. I noticed how the kids were berating her for everything that she was doing:
- texting during the dinner - talking to some 20 something women about something that teed off my 14 year old - flirting with the waiter
It just went on and on. After dinner (kids were with me) I had a talk with the two oldest and told them that they needed to start cutting their Mom some slack. I can't imagine anyone who would want to have their every action criticized like that. I could see that it made her just not give a rip about what she did.
I guess what I'm saying is that at some point we truly have to let go of all the mistakes and hurt in hopes that a new relationship can be born, one that is healthy as possible for the children.