I am so, so sorry they treated you that way. I agree, though, that what you did was far more meaningful than the JW Infomercial that surely was her memorial.
I have been through something similiar lately over the death of my grandmother, who emotionally, was my mother. Links below to my threads if you want to read and know that you're not alone.
I am so sorry about your mom, and also for the terrible way they treated you. Good for you for walking out, we have to draw the line sometimes, don't we? I know that not going to my grandmother's memorial was absolutely the right decision.
http://www.jehovahs-witness.com/6/81221/1.ashx
http://www.jehovahs-witness.com/6/80502/1.ashx
hugs
essie