She disclosed that clients' money worth $190m (£110m) in both cryptocurrency and normal money is in "cold storage" and only her late husband holds the keys.
The debt filing comes weeks after Robertson announced that Cotten had died - an event she described as "a shock to all of us".
It is understood that save for some money in what is effectively a petty cash drawer, virtually all of the exchange's funds are locked up, meaning customers are unable to withdraw their dosh, practically speaking.
Christine Duhaime, a lawyer and founder of the Digital Finance Institute, said users would have little recourse to recover the funds.
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The Canadian cryptocurrency exchange QuadrigaCX owes its customers about $US190 million, or 249 million Canadian dollars, according to CoinDesk.
The online startup can't retrieve about US$145 million in Bitcoin, Litecoin, Ether and other digital tokens held for its customers. An additional CA$70 million ($53 million) is in the form of government currency. It warned that customers might take legal action against Quadriga if the problem continues.
Cold wallets are encrypted and offline, making access to these digital storage units exceedingly hard if you don't know their access codes.
They say about 115,000 Quadriga users hold balances in their personal accounts in the form of cash obligations and cryptocurrency.
"A cold wallet or cold storage is located offline and is a safe space to secure coins", explains Robertson, in her affidavit.
Robertson says that she has received online threats as a result of the freakish deadlock.
"Gerry ran the business through his laptop, mostly at our home, but also wherever he happened to be", she wrote, saying home was mostly Fall River, a suburban community outside Halifax. Based on company records, she said the cold wallet stored $180 million in Canadian dollars ($137 million in United States dollars), all of which is now inaccessible to QuadrigaCX and more than 100,000 customers.