According to the AG of Colorado, at http://www.ago.state.co.us/FAQ/CLM_FAQ.cfm.html
A common law marriage in Colorado is valid for all purposes, the same as a ceremonial marriage. It can be terminated only by death or divorce. The common law elements of a valid marriage are that the couple (1) is free to contract a valid ceremonial marriage, i.e., they are not already married to someone else; (2) holds themselves out as husband and wife; (3) consents to the marriage; (4) cohabits; and (5) has the reputation in the community as being married. The single most important element under common law was the mutual consent of the couple presently to be husband and wife. All the rest was considered evidence of this consent or exchange of promises. The only time requirement necessary was time enough reasonably to establish these circumstances. When proof of common law marriage is required, such as by an insurance company, a signed affidavit can be presented. For a sample affidavit, click here.
Common law marriage is a term used to describe a marriage which has not complied with the statutory requirements most states have enacted as necessary for a ceremonial marriage. The name came from the fact that these marriages were recognized as valid under the common law of England. In 1877, the United States Supreme Court stated, in an action which questioned the validity of a nonceremonial marriage, that marriages which were valid under common law were still valid unless the state passed a statute specifically forbidding them. Meisher v. Moore, 96 U.S. 76 (1877). Since the Colorado legislature has never enacted such a statute, Colorado is part of the minority of states which recognize the validity of common law marriages.
If you desire a legal opinion relating to a specific situation, you should consult your own attorney.
From reading that, I do not know whether or not you are married under Colorado law. She claims you are, you say you did not meet requirement #2: "holds themselves out as husband and wife."
This is not a question that can be definitively answered by anyone other than a Colorado attorney, and even then it might have to be settled in Court.
Sometimes the law is definitely unclear. Sorry I cannot give you specific advice other than to consult an attorney in Colorado, but I hope the above information was helpful.