No, you should not have been given notice. From what you have said, he was no longer on probation. If he had been on probation still, the prosecutor would have probably contacted you to let you know that your husband was asking for an early termination and probably have asked for your input. Since he was off probation, there was no need for you to be involved. As for the DUI, the conviction is still priorable. If he were to pick up a DUI tomorrow, it could (and probably would) be filed as a second DUI. So, yes, in this case you are wrong.
No duty to inform you. You are not a party to the litigation [DV or DUI case]. Code section is PC1203.4.
The above is not intended as legal advice. The response does not constitute the creation of an attorney client relationship as this forum does not provide for a confidential communication.