Sorry wasn't able to come back last night scarlotti and won't be around much today.
I think you should perservere with the Relate sessions absolutely, but do think that you'll get the best out of them as a couple if you're honest there - and with eachother in between sessions. At the moment, he seems to think the point of these sessions is to revamp your sex life, whereas your objectives are multi-faceted. His are rooted in the marriage continuing and yours are in the marriage ending.
The problem with controlling children like your H is that they tend not to believe threats - and so all the frustrations you've expressed over the years have resulted in no particular penalty for your H. In fact, the only one that causes him any real problem is the lack of sex, hence he's at Relate to try to stop that particular "punishment".
I think it would be worth writing down (even here) what you are wanting to get out of these sessions. Ask him to do the same.
I do think he needs to know how imperilled the marriage is - and that his best chance of saving it is to continue with the counselling. There's a sense that if he really knew this time what was at stake, he might confront at last some of his behaviours.
The counsellor will want to be as even-handed as possible and will not want your H to feel "got at" and so she is reinforcing some of his qualities and seeing the "good" side of his faults. However, given the advice you've had from other posters, be very careful that the counsellor sees what came first - his lack of personal responsibility or your critical behaviour.
It is terribly important that you discuss the notion that he is displaying controlling manipulative behaviours and that your behaviour is borne out of sheer frustration. The proof is in the pudding. You don't want this to continue - whereas he does. That's because apart from the sex, he is the over-benefited one in the relationship.
However, if he did but know (and this is where the counsellor can really help) it is a horrible life for him that could be so much better. He's probably got used to being treated with a lack of respect and even contempt. He possibly doesn't even question it. He needs to see a life where because responsibility is taken equally for everything - and love and respect run like a golden thread throughout the marriage - his life could be so much better.
It would be perhaps a good idea for a session to discuss what his ideal marriage would look like - and for you to do the same. You have both perhaps got to the point where you don't think that's possible with eachother, but in truth, unless there is a real commitment on both sides to try to change the scripts you have been enacting, you will never know what that good marriage could be.
I suspect many couples enter Relate with different agendas, but they normally have some idea that this is the case. My discomfort in a way is that your H doesn't seem to know your agenda, whereas his is pretty open.