Just like newacct wrote, you have a 10-year ban. Just because you are a Canadian citizen now does not get rid of your previous unlawful presence. Aside from violating the terms of your K-1 visa (you did not get married within 90 days of entry into the US), you overstayed for 3 years.
You don't think the US government will know when you left the country? Try plane manifest. Every airline that leaves the US has to submit to the US government the plane manifest, which will contain your name and when you left the US. Not only that, Homeland Security will have your fingerprints in their database, given that you applied for a K-1 visa. Every non-US citizen entering the US gets fingerprinted at which point the computer will pull out your immigration history. You can be sure the immigration officer will know you've overstayed and that you're now trying to enter the US as a Canadian citizen on the VWP (visa waiver program) without applying for a tourist visa and a waiver of the 10-year ban first.
Even after your ban expires in 2020, you still are not allowed to enter the USA on the visa waiver program for Canadians. That visa waiver is only available to Candians who have never committed an immigration violation in the US. Because of your previous immigration violations, you are required to apply for a tourist visa from Canada even after your ban is over.