I hope you've done or are doing the things devasted listed, especially the NC with the OW and the completely coming clean. Another thing is complete transparency. I know it's almost instinct/reflex to omit things to save our BS more pain but it's the lies (even of omission) that really do the most damage.
I also know the frustration of not knowing what to do, especially when a trigger hits.
As for being alone to deal with this... well, you're not. You have 40000+ members here to help you. Some farther along, some about the same place, some behind you and on both sides: WS who have BTDT and BS to help you understand what yours is going through at each stage.
All affairs are variations on a theme. No one has 'Beethoven's 5th' to everyone else's 'Chopsticks'.