My exwife filed a small claims case against me without first notifying me what she wanted. Shouldn't she be required to so I can pay without judgement

You can pay without judgment right now, if you and your ex-wife can agree on the amount (as a practical matter, if you are willing to pay the amount your ex claims, the Court will likely force this result on  your hearing date.)  If you can't agree, but you are confident that, even though you owe her something you do not owe her as much as she claims, most jurisdictions have procedures whereby you can make an official offer of settlement and if she refuses and then is not awarded more in Court she can be responsible for  your legal fees.  In a small claims case, there may not be any legal fees, but you should nevertheless look into this because your state may have a slightly different rule which could benefit you.