As for the mortgage, as others have said, he doesn't have to pay.
it's not right for him to pay CMS AND mortgage
These statements are nuts
The mortgage is also his responsibility. It's a jointly held asset. If the OP pays the mortgage & he pays zero to it, he will retain 50% ownership & that proportion of the equity, as well as being able to make decisions about what happens to the property.
If he does not want to pay his share of the mortgage, then he needs to (with legal advice or via mediation), work out what to do.
- House is sold, equity split, with OP aiming to get more of it due to providing principal accommodation for 2 DC
- OP gets a mortgage on her own name, takes over the property & will also have pay exH a share of the equity (and that's the problem as she may not have that to pay)
- An arrangement is made whereby OP stays in the house till an agreed date eg youngest DC finishes education & then house is sold with agreed equity split in favour of OP.
What he can't (or rather should not) do, I'd move out, pay nothing to the mortgage, and still expect to have all the rights of being a joint owner with none of the responsibilities.
The statement 'it's not right for him to pay CMS and the mortgage' - ok, then, he reaches an agreement with OP.
I have been in this position for several long years and finally getting it sorted (the legal wheels in Ireland move v slowly).
I can't stand this narrative that because he has to pay rent on a new property he can ignore existing financial commitments. No, he has to bloody sort them out!
OP, go back to your solicitor. Make plans to divorce, and sort out the property in that way.