My exhusband agreed to pay all the attorney fees of our bankruptcy. Our divorce was finalized and now he is coming back at me saying now he wants me to pay half. Can he do this? I live in the state of California.

Sure he can come back and ask you to pay for anything he wants, does not mean you need to, or that you should even worry about it, Perhaps laugh at him, or how about just not talking to him.

Unless that was part of the ending judgement then you don't owe a dime for his attorney. He would have had to ask for that going into it.