You're not alone. It's one of the biggest concerns for single moms and dads, especially if custody has never been formally established. If the prospect keeps you up at night, consider your options -- whether you have a lawyer already, are ready to start finding one, or are contemplating filing pro se.
Start by reading What to Do When Your Ex Files for Custody to learn more about your options. Then get to know your state's child custody laws so that you'll be prepared for whatever case your ex might try to make.
Finally, as you consider your options, take the time to document your observations -- from phone calls to texts, emails, visits, and more.
Photo © Cristian Baitg, 2009