stop letting my mother's opinion ruin my life

I figure that some day I’m going to grow up and stop letting my insane mother ruin everything for me, but so far, the only way I’ve avoided it is to live far far away from her, but now that isn’t an option. So anyone got any ideas of how to avoid this situation?
I’m forever letting her pessimistic world view effect my life, because every time I’m near her, I go into the exact same mind set.
I’m really beginning to wonder if insanity truly is maternally hereditary