The Realtor makes an offer -- Chapter 3: the negotiation

The Toluca Lake townhouse we like is listed for $439,000.  I believe the comparable sales in the neighborhood and complex show it to be worth about $425,000.  On Monday night, my husband and I made an offer of $430,000.  We have 20% down, are pre-approved by a direct lender, and can close in 30 days.  I will be taking my share of the commission, which is 2.5%, which will help with our closing costs.  We might go to $439,000, but I'm concerned about the appraisal coming in at that value.

The townhouse is still not available to be shown as painting is being completed, but will be ready right before Thanksgiving for Realtors and their clients to view.

On Tuesday, the listing agent tells me the seller wants to wait to respond to offers until after her Sunday-after-Thanksgiving open house and is stuck on her asking price.  Fair enough.

On Thursday, Thanksgiving Day, the listing agent calls me to tell me there is another good offer in and it is comparable to ours in price, terms, etc.  She sends a $439,000 counter offer to us.  We sign off -- appraisal be damned, my husband really loves this place -- and send it back.

The listing agent calls to tell me that she is representing the clients who are bringing the other offer (I wondered how anybody else got in to see it so soon) and they too have signed off on the full-price counter.  This goes without saying between agents, but she will make 6%, not 3.5%, if she double-ends this.
Next: how will this end?