Yes, I can see the problem, and I do not know how divorce arrangement work where you are, but can you not voice your concerns to your lawyer - that you want a commitment to counselling for a certain period, because you feel it is in everyone'e best interest to continue with it. It doesn't seem like an unreasonable thing to do. It is always possible that your h will continue anyway, and it doesn't leave the boys high and dry if he walks out. Any reputable therapist will point out the damage to the children of walking out of therapy
The theory of divorce is that it puts the interests of the children first . . . . . although in most cases I feel that the parents not getting divorced in the first place would be best, but there is no reasoning with a MLCer and their concept of a loveless marriage.