H and I have been living separately for almost 2 years due to this .
During this time he has been having counselling, still is, and also on antipsychotics and antidepressants. I did counselling for just over a year, which was extremely helpful as I now feel quite good. We occasionally have one or two joint counselling sessions to iron out parenting issues which we can't agree on, and ways of talking to each other. I've had legal advice so know where I stand.
One revelation from the counselling has been that H was quite seriously abused during his childhood. This explains his secretiveness and sex addiction (see other thread).
Recently we have been getting on a bit better. However, one thing which we just can't get past is that H takes everything I say as a criticism. We have talked about this in joint counselling: the counsellor said that many things I say ARE criticism - fine, but why shouldn't I say when I don't like something he does? - but some situations are just so bizarre that I don't know how we can get past this.
For example, recently H and I were talking about childbirth and what an amazing feat it is for women. He thought I was saying he is less of a person than me because he can't give birth. 
Seriously. This has never even crossed my mind as it is a completely outlandish thought.
It is as though when I could be seen to be doing something well it takes away from his position - we can't both be great at different things, if I'm pleased with something I've managed to do, he sees it as a criticism of him for not doing the same thing. But this is not how I think at all, it doesn't even cross my mind to expect him to do everything that I do. Similarly, because of his reaction to every perceived (nonexistent!) slight I wonder if he sees me as deficient when I don't achieve things he does.
I don't know if this makes sense to anyone. Basically, sometimes I'd like it if he said nice things about difficult things I've managed to do, but whenever I bring this up, he completely overreacts, cries, gets angry, and misunderstands my viewpoint completely. The result of his reaction is that my feelings are completely disregarded (any conversation about how he hurts my feelings turns into one about how I'm hurting his feelings by mentioning my feelings!) and we never get anywhere. It's like he has some module missing in his mind or something!
The other thing I was wondering is whether anyone has ever successfully reconciled with a (former) sex addict. I am insisting on living separately for the foreseeable future (and beyond) because I really like it, but we more or less still have a relationship. I am still trying to decide whether I want to carry on or completely call it a day. Despite all of my counselling I still haven't come to a conclusion yet.
One issue is that he will have to decrease his medication soon, and I am seriously dreading it. It took 6 months for him to find a combination which worked for him, and during those months he frequently stormed off crying or in a rage, turned up late for contact with DD, behaved erratically and was generally awful to me. This obviously makes me worried about how to arrange contact when he changes his medication as any perceived limitation of his time with DD will be met with threats of legal action etc. But this time DD is a lot older so will be more distressed by crazy behaviour and non-responsiveness (he zones out a lot).
I know I should finally 'leave the bastard', but tbh, it's more complicated than that.