My thought is skip the other mother and go straight to the pastor, tomorrow. That way your daughter continues her friendship, and you get straight to the source, avoiding any possible drama with the other mom and her daughter.
Second, make a list tonight (anyone got specific agencies to mention for Stronger?) of agencies in your town, shelters, SCAN (stop child abuse now), and do you have 311, that number that you call to find out who to call for what? Also, you might contact the guidance counselor at one of your kids' schools. They may be able to hook you up with some resources. And call your family. You may need to move to where they are, quickly, and they just might have a way to get you home.