Ok, so your wife is a recovering addict who suffers from bi-polarity, ocd, and dissociative disorder, and she's saying she wants to be submissive to you? Do I have that right?
I'm no mental health specialist, but I think you're treading on very dangerous grounds. BDSM can be confusing, frightening, and overwhelming for a fully stable and mentally healthy person; trying to do it with a woman who suffers from as many psychological issues as your wife is going to be extremely challenging. BDSM involves a lot of contradictions and paradoxes--you hurt the person you love, the sub wants what she doesn't want, and so on. These contradictions require dom and sub to have a firm foundation of rules, guiding principles, and ethics to help them stay oriented while their turn their perspectives upside down and go down into some of the darkest parts of the human psyche. It's not too hard to get lost, for consensual play to turn into abuse, for doms to cause real harm to subs unintentionally, and so on. I've seen subs have sudden outbursts of tears or anger during play (my first slave once broke down in the middle of a flogging and cried uncontrollably for half an hour about how his mother never loved him). Not everyone can handle the intensity of BDSM, and I suspect that your wife could be one of them.
But it sound like you really want to try this out, and she wants it too. So here's what I'd suggest if you decide to explore.
1) Confine your BDSM to bedroom play only. Don't try to do lifestyle BDSM (in which she gives up control over her daily life, does all the chores, and obeys all your commands). Consensual slavery is remarkably challenging emotionally, and I could easily see it overwhelming her and triggering a relapse to her addiction, a major depressive incident, or something like that. If she's Bipolar and OCD, she has a tendency toward extremes, and lifestyle BDSM might really draw that out of her.
2) Keep your BDSM light and playful. Do spankings, light torture, light bondage, control of what sexual activities you do and so on; don't do heavy pain play, verbal abuse, humiliation, or serious punishment. Those latter items are things that tend to bring up deep emotional issues and tend to flip a normal relationship upside down (you're insulting the woman you love, treating her harshly and so on). Your wife needs to feel at all times that you love and respect her and that she has a right to stop play whenever she needs to. If you decide to venture into those darker areas, do it very slowly and stop if she starts to have a serious reaction. Make sure you keep fantasy play and your real relationship firmly distinct.
3) Make sure she has a safe word and understands that she can stop at any time. Subs want to please their doms, and your wife has a tendency to go to extremes, so her instincts are probably going to be that she has to endure as much pain as possible. She needs to understand that safe wording isn't failure; it's a basic health and safety technique. She needs to accept her limits.
4) If possible, talk to her therapist about this. This is tricky. Many therapists see BDSM as unhealthy, even though it's not considered pathological by the mental health organizations. Hopefully your therapist is kink-friendly, or at least open-minded. Being able to discuss your kinky behavior with a trained specialist who understands your wife's issues would be ideal, because the therapist might be able to warn you away from forms of play that might set your wife off.
5) Before you do this, get some books on BDSM (the Newcomer's FAQ has a good reading list) and learn what constitutes healthy BDSM. That's basic advice for any new BDSM couple, and I think it goes double for you.
Again, my advice would be to not do this. There are lots of subs out there who are too emotionally damaged to do BDSM in a way that is safe and healthy, and it really sounds like your wife falls into that category. But obviously you know her way better than I do.
