You can be sent back to Canada if you don't have the proper visa to be in the U.S. As a spouse of an American citizen, your husband can file a petition on your behalf for an immigrant visa so that you can stay permanently in the U.S. As to the question whether your marriage is legal, you need to check what the marriage requirements are for the State you were married in. Formalities and requirements (i.e., marriage license, blood tests, ceremony performed by someone with the legal authority to perform marriages, etc.) vary from State to State. If you haven't already, you need to obtain a marriage certificate (not the same as a marriage license). The marriage certificate is the document you need to prove that you and your husband are married. A local immigration/family law attorney in your State should be able to address your concerns. Good luck.
