Can my attorney withdraw for nonpayment if I can't borrow money any more?

Yes. Payment is required for work.

If you cannot afford to pay for additional future services then a court will USUALLY allow the attorney to withdraw from the case for non payment of fees. There are exceptions such as right before a trial. However in that case a Judge MAY let the attorney withdraw, and continue the trial date to allow the client time to hire new counsel. One consideration may be that if the spouses are creating more litigation by spite, hate, principals and/or not resolving issues that should be resolved, the court will not force an attorney to continue representing that client.