"We've had more than a year to realize this wasn't the case from Iraq.
Attacking Iraq anyway is therefore the worse crime a country can commit."

As far as I know, Saddam never fully complied with cease fire agreement. More precisely, Saddam never fully complied with the section of the cease fire agreement regarding WMD- and also there are other sections he didn't comply with.
The "proof" of Saddam non-compliance with the cease fire agreement was the UN sanctions imposed on his country. If Saddam had chosen to follow his agreement, there would not have been sanctions.
The inability of the UN inspectors to not finishing the main part of their task [regarding WMD] was not due to the inability of the inspectors, rather it was due to Saddam hindering and not assisting them in completing their task. If Saddam had chosen to comply they would have taken a relatively short period of time- a year or so. Instead after 12 years the inspectors were still not getting "complete cooperation" per Blix's report [with the Coalition troops massed at the border]- though the inspecters were apparently getting better cooperation.

One way to look at it was that Saddam didn't really own his car- there was a lien on the car. Saddam got a loan to get his car out of the automobile impound, then promptly did not make his monthly payments- he would pay some money towards the monthly payments & if the police showed up he might pay most of monthly payment- but never did he actually pay one monthly payment- nevermind actually paying off the loan.
And you can't make the excuse that Saddam was too poor to pay his debt- he simply didn't want to pay his debt.