Monocle, all I can really say is something I learned last night at dinner. If things start to break down, begin acting and thinking positive. Literally deflect the negativity of the situation. Bring up conversation when those awkward angry silences kick in, defend what you've done, but in a respectful way. If your mother calls you a little bitch or something related, don't react.
I understand your mother is always going to be abusive, but if you feel abused, she's won.