Not getting married is such a huge mistake. Oops, I've said it. That 'piece of paper' is a legal contract. It acknowledges your relationship in society and protects your rights in the god forbid event of things going wrong.
I am so sorry for your lonely position, which I am in too. What I have learned is that the children are used as part of a triangle so that there IS no adult time. He is 'superDad' (mine was too) so that he doesn't have to interact with you.
When the children were born this split went off in his head, and I became simply 'mummy' and housewife. Like you I ceased to be a human being. I also became hugely resentful about housewife duties like you, and like you OH my H was very resentful of the state of the house.
We never, ever had time together. Never. I remember my futile attempts, so make dates, talk to him.
Now I know through Relate that men who are incapable of intimacy arrange their lives so that they don't have it. They choose workaholic jobs, shifts, expat/oil rigs etc., live through the kids, have affairs, to keep you at arms length.
All I can suggest is that you insist you go to counselling. And if he won't go with you, still go and not secretly either: apparently a women continueing to go to counselling even after he has declined, is the biggest thing to overcome his denial that something is wrong.
I would not advocate a power struggle, but to 'give up' on trying to change him (ie accept him for who he is) and really work on yourself: your training, work development etc. When you accept him for who he is, you can give yourself permission to go out etc. (I did this, it didn't change him in the slightest all we did was have separate lives. But at least I got some friends, a bit of emotional support).
The only other thing I can suggest is that you get his acknowledgement of stuff you do down in writing (emails etc).
All the best, think for the long term [where will I be in 8 years' time] and I know how lonely you are.