BM, you're right, things do become clearer. I regret that I accepted so much of the blame in the beginning. It just gave my STBX more confidence and justification. I enabled him. If I had taken action sooner I might not be in this tangled legal mess that I'm dealing with now. A year ago my STBX seemed to feel some guilt and we were on speaking terms. There also wasn't an OW in the picture then, to my knowledge. As time goes on he is more detached and selfish. The OW has lots of money (not sure where from, maybe she's gambler also) so the two of them together are happy to fund a legal battle. I can't imagine that any self-respecting woman would put herself in the middle of this.
The addiction is definitely a factor, not necessarily fueling MLC, but another sickness that creates narcissitic, secretive behavior. The two together is a horrible nightmare. I contacted GA last year and found a meeting in my area. I haven't gone yet since it conflicted with my IC appointments. I'm glad that you're getting much needed support through Al anon.