D.B.
J., I would wait til you are around 12 weeks to announce your news. Have everyone over and tell everyone, and DON'T look at your mother. You don't need this in your life or memory, thinking about her reaction.
If she says something to you about ignoring her, tell her that you didn't want a replay of her actions from last time, that it hurt your feelings and is something you can't forget. I hope that this will at least keep her from making any negative comments. If she says something negative anyway, tell her you don't want to hear it, and walk away.
Congrats on your pregnancy!
Dawn