Based on the posted facts, your company made false representation of a material fact concerning the historical purchases, intended to induce justifiable detrimental reliance from the partner company, and the partner company was damaged as a consequence.
And, that is the common law definition of civil fraud.
Your acts don't disclose the extent of the damages caused, and it would be somewhat dependent upon the respective benefits and burdens of the two companies to the deal. Nevertheless, the partner company could demand reliance damages, which would be what the partner would have received had your company's assertions been true. And, that amount could be substantial.
Also, for a proved fraud, punitive damages are available, so that could add to the return. And, since this is contract fraud, the partner company could get attorney's fees, assuming that they are called for in the contract.
So, this could end up being a rather expensive litigation.
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