It sounds like you're facing a complex situation that requires immediate legal assistance. Colorado law allows for non-biological parents to request custody under certain conditions, especially if they have had physical care of the child for a significant period, as seems to be the case with your ex-husband. Courts in Colorado also consider the best interests of the child, which can include a variety of factors such as the child's relationship with both parents, the mental and physical health of all involved, and more.

Given that your ex-husband is not the biological father and you are the biological mother, you generally have a fundamental right to make decisions concerning your child's care, custody, and control. However, the court can grant parental rights to your ex over your objections if special factors justify the court's interference with your fundamental right as a parent.

To learn more about non-biological parental rights review our article "My Teen Wants to Live With an Ex Who is Not Their Parent."

Here are some steps you can consider:

1. Consult a Family Law Attorney: Given the complexity and urgency of your situation, consult a family law attorney who is experienced in Colorado child custody laws as soon as possible. They can guide you through the legal process and help you understand your rights and options.

2. Gather Evidence: Collect all relevant documentation and evidence that supports your case for why it's in your daughter's best interest to live with you. This could include evidence of your relationship with her, your ability to provide for her needs, and any concerns about her current living situation.

3. Court-Appointed Expert: Since your daughter is 15, her wishes may be considered by the court, but they won't be the sole factor. A court-appointed expert may interview her to assess her maturity and wishes, which will be included in a report to the court. Read "At What Age Can Your Child Decide Where to Live?" for more information.

4. Defend your parental rights: You need to actively participate in the court proceeding and present your case. As mentioned, I would recommend that you hire an attorney to assist you.

5. Stay Informed: Keep yourself updated with all court proceedings, and make sure to attend all hearings, either in person or virtually, especially if you're residing in a different state.

6. Communication: Try to maintain open communication with your daughter to understand her wishes and feelings, which could be important in court. (This assumes that there is not a court order preventing you from doing so.)

Given the seriousness of your situation, it's crucial to consult a Colorado attorney to assist you. If you would like a free case assessment with one of our family law attorneys please go to https://www.robinsonandhenry.com/locations for various ways to schedule a free case assessment or call us at (303) 688-0944.