Thank you for your response.
The situation does seem rather unfair with the mortgage payments being so high.
You are probably aware that the courts main priority is the housing needs of minor children. From what you have said there appears to be sufficient equity to sell and downsize but this is going to mean that your ex might have to move within the 10 mile radius that you have stated. The children's schools are going to be a factor and whether they can still attend their current schools from a slightly outer location.
The key is arguing that downsizing is possible is getting lots of information on available properties so that a Judge would consider the current 4 bedroomed home as surplus to needs for your ex and 2 children.
You also need to argue that your needs to be bolstering her own income position as with the children at school then she could look for more than 16 hours work and you at least want to see some proof that she is making an effort to do this.
You do not have to accept that that house cannot be sold and downsizing happening, you can argue that it is possible and a Judge will have to make a decision.
A lot of this is going to depend on what your ex now decides to say in the future. It's likely the court is going to order a hearing in relation to the proposed consent order and if your ex confirms he agreement to the same at court then thi smay well be still approved.
I hope that this helps you
Positive feedback is gratefully recieved