If your husband can take on the mortgage on his own, then you can both apply to the lender to do a transfer of equity. That would mean that the lender would agree that the title and the mortgage be transferred to him. You would have to reach an agreement on when and how you are going to be paid your share of the equity if that is an issue. If, however, it is not an option for him to take on the house, then you won't be able to get out at this stage and you may have to wait for completion so that the house can be disposed of. Happy to discuss further. I hope that helps. Please leave a positive rating so that a I am credited for my time.
It might be that a different lender would be able to help. Let me know if I can help you in the future. Kind regards.