What a terribly sad story. Here is the part I don't understand: why does the RC church regard a non-Catholic marriage so binding as to prevent a Catholic marriage? I'm not saying it is wrong; just wondering how the policy is taught.
"Sally" needs to clear this up, not cry. She needs to find the money for a good private investigator who will get her the facts and the records she needs, without her having to contact him. For all she knows, he may be dead or have been declared incompetent from the time of his first hospital commitment.
But on top of that, if people are baptized Christians, they are certainly (though imperfectly) members of the Catholic Church, no matter what "denomination" they were in. And according to the Catholic understanding of marriage,. the "ministers" of marriage are the spouses: the wife confers marriage on her husband, the husband on his wife. Therefore, their marriages establish a permanent, till-death Sacramental bond recognized and respected by the Catholic Church!!
We honor these couples by taking them at their word. Our default position is that their marriages are canonically valid, unless it can be proved that they were defective from the git-go.
Your point that the ex might be dead by now, is a good one. Sally’s parents are moderately well-off, and Fr. Pete has already urged them to hire a professional PI. I actually have hopes for this one, but it’s going to take a long time, and Sally is struggling and suffering. It’s very hard to watch this happen. And she hasn’t even the Sacraments to console her.