I know someone who had a civil marriage ceremony about 15 yrs ago. The “marriage” is on the rocks and both parties are in the process of getting a divorce. One party is a baptized catholic. I have been encouraging this individual to get the divorce (am I wrong here?) The marriage is beyond repair…once the divorce is finalized, can the catholic pursue another marriage in the catholic church?
I assume that there was no Catholic Church permission for the wedding. It is then a case of Defect of Form, since it was not in compliance with Church Law for valid marriage. This is the easiest case to get declared invalid; just some simple paper work. Her parish priest can prepare the paperwork and send it to the Diocese for approval. It takes a month or so. It requires some documentation from her - her Baptismal certificate, their marriage license and the divorce decree. It probably requires a witness statement that the marriage was never convalidated.
I listed this out here to give you a feel for the situation. My memory isn’t that good; so see a priest and rely on him for accurate information.