You reached an agreement with him back in March.
You were both independently advised by solicitors.
No, the courts will not order him to pay half the mortgage.
If he takes you to court, there is really no knowing what the court will do. I would imagine that they would ask you to honour your agreement. But they might give you time to do so.
Your best approach is to try to find someone else - maybe a relative - to take out a mortgage with you to replace your mortgage with him.
Another possibility, although it's a long shot, is to ask a Credit Union.
Brendan