My ex forged my name to that vehicle insurance return about 5 years ago. I got a copy of the endorsed check. My lawyer said it was forgery. The amount (my half) was about 82.00… not worth the hassle of criminal prosecution. I did have it addressed in the divorce decree.
I do not think you can sue the bank, I am pretty sure you can sue your STBX as long as this happened after the date of seperation. If it would be woth it, you may even have a criminal lawsuit.

During a marriage, if any kind of check is issued to both spouses, is it forgery if one spouse signs the name of the other in order to cash the check? I know forgery is forgery, but does marriage make any difference? I’m sure it happens, but what is the “law” on this? Can one spouse “sue” another because of this or sue the company/bank that allowed it? Thanks.