Definitely see if you can break this agreement. I know that the 3-day rules applies to a lot of things; maybe it will apply to this also.
A nephew of mine went to mediation over a roof on his new house. His was binding mediation and he lost; he would have been better off if he had not consented to mediation and sued the previous owners instead. As a result of this experience, no one in our family would ever agree to binding real estate mediation again.
Oh, and you have to realize that not all lawyers are competent! I would call another lawyer and ask if you can rescind your agreement. Most lawyers will give you one free phone consultation. Since you won't know who will get back to you first, I would call several lawyers to ask for a callback the same day.