Give yourself some insurance
If at all possible, try to get some of her screaming and innapropriate behaviour on video...hook up a web cam on the living room computer and eat your hard drive every day.
When it comes time for custody it will be invaluable. Usually divorce cases are "he said she said" - if you can demonstrate this stuff you will have a (very very shapely:) ) leg up.
As a somewhat recent divorcee
J
From my personal experience the insults and belittleling stopped a few months after I moved out. That was when I realized I was done. For me personally I asked God for a sign if there was something ooutside of my last marriage be it career, personal goals, another person even but to please show me a sign even though I already knew in my heart that I loved and cared for this person but I was no lomger emotionally there. My lack of emotion and the insults that my son was subject too, made me think if I at leat remove that factor we all can begin to heal. Divorce can be even more traumatic to a child, but i grew up in a house of 18 years of arguing, bickering....my son and i have a stronger bond now that i don't have my ex interfering and insulting me all the time making me feel small. Is that the example you want your child to see. I am not saying anything, but to look at your childs welfare for the long term. Will actions now judt be better for her in the long term constantly seeing her father berated or her parents in constant conflict. Will it benefit her to see you resolve the conflict and how you do and how you rise above it to be stronger person even if that includes counceling as opposed to separationg. My experience is just one, but my family, my son, my ex are all much better at getting along now that his parents faced some truths. My path may not be yours, but I just beg of you to consider how you would want her to spend her next however many years and how she'll handle relationships as she gets older.
Just my opinion.