I think that you need to seek help here.  Generally speaking, inheritance is tax free as the estate pays the taxes prior to distribution.  So why you are being taxed on them I do not understand.  Now, you need to take your ex back to court and ask the judge to subpoena the necessary records.  Or you can look in the estate file for the person who left her the money - it is a public record - and try and put together the information you need.  Good luck.