I am on medication now which stabilizes things considerably (after 8 years of slowly worsening). They finally gave me a stable emotional base from which to begin work on my more fundamental issues (FOO, insecurity, self-esteem) and our relationship.
But a lot of damage was done before I was diagnosed or was unfaithful. I denegrated/judged those around me to patch my self-esteem, reacted disproportionally to emotional conflict and was unpredicable. It was horrible for her. Those combined with the hyper-sexuality that can come during the manic phase resulted in 2 one-night stands (thank god not any worse).
D-day was a mess as I was paranoid, unstable, avoidant, and irrational in justifing/hiding everything (pre-diagnosis). My behavior on D-day was probably the worst of it all as she feels little trust in what I say. (you wouldn't believe the paranoid emotionally-crushing things I believed where being seduced to feel better for a moment seemed justified (read irrationally selfish).
As I said, things are more-or-less stable but I still have milder moods swings and still memory loss. I've tried to explain so expectations can be re-set. Unfortunately, she often sees my bi-polar explanation as a realy convenient responsibility-free excuse.
I'm getting a lot better at staying in perspective when things get heated (and sometimes even more mature than her for a change). So slow improvement but it's still hard keeping in mind that I need to initiate conversations about infidelity. SI really helps identify things for introspection and discussion. But one, I'm inherently avoidant (coming here is hard even though it makes things better). And harder when I'm depressed/paranoid. Secondly, it's hard to remember to initiate conversations about what I learn. That initiate part seems really important. (P.S. Writing this makes me feel like I'm whining about how difficult things are for me rather than just doing the really hard thing).