If the phone has a SIMM card, you can try ordering a SIMM card reader online. They cost about $5. I recovered several messages from my son's phone where NJ was coaching him in how to act with me. However, in my case they were already there. If they have been erased I doubt this work unless they were previously backed up to the card.
Deciding to go forward with a divorce is kind of like joining a brotherhood. However, it is a brotherhood that you really don't want to join.