How binding is a separation agreement?

My husband and I signed and had notarized a separation agreement earlier this year. In it, “husband” agreed to move out of the marital residence by a certain date so that we can sell it (he and all his stuff are still there) and that in the event we didn’t agree on a purchase bid, we would ask our real estate agent to make the final decision. We have a potential buyer who offered asking price until the appraisal came in $20k low and inspections showed a number of deficiencies. They’re now offering to pay appraisal price for the house “as is” (they do repairs). I would like to make a counter offer but my husband refuses to go down in price. Our agent is concerned that we will lose our buyers if we make no concessions. There is a severability clause in our contract.

So, my question: how binding is our contract, and how do I go about enforcing it so that we don’t lose these potential buyers?

A separation agreement is enforceable just as any other contract is. If your spouse is refusing to abide by the terms of the agreement your remedy is to sue him for breach of contract.