Check the papers he handed you. There should be a court name on the top (e.g. 2nd division of the x county of y state). Call that county courthouse clerk’s office and ask them if they have a copy of whatever divorce document was handed to your mom.

I’m a bit surprised that no lawyer would give you a free consultation. Keep checking the phone book – maybe you can get a free legal opinion from an attorney in your state (that would be the best answer).