Seeing as Canada doesn't have a database about this like some countries and we have no way of really prooving we are single other than our declaration it can be tricky. When I was living abroad and thought I need such a document I went into the local Canadian embassy (not in Canada) and they said I could declare I was single and they would print a document saying that Canada does not have such single status documents but that you have sworn it to be true you are single and not with somone else. SO I say go into the local office and if you can't ask you wife to go in on your behalf. ask them if they will make a document saying no such document is avail but to the best of their knowledge you are single.....
Here is a sample of a declaration for single status,you will have to change a few things then get it notorized by a lawyer,i had to do the same to get married.http://www.drembassy.org/english/Consular%20Services/sample_marriage.pdf
