parents abusive to each other, can't divorce. any advice?

my parents have an awful relationship with each other and get into huge fights at least once a month for the last 8 years. i've asked a friend to call the police on them once before because i was too afraid to do it myself. someone came and simply told them that they can fight as much as they want as long as it's not in front of the kids. and, of course, they kept doing it in front of the kids. last night i was up until 6am because they were screaming, throwing furniture, etc. one time (a few months ago) i was screaming and begging for them to stop until i threw up from yelling so much and how loud they were. my mom has threatened me multiple times not to call the police because i'll get taken away by cps. i don't want that either but i want this to stop and i'm unable to stop it myself. my mom has tried to divorce him several times, but she can't get a job and she has little to no financial support from her family and all of her immediate family is dead. plus, she doesn't even have the money to pay for a divorce because she is a victim of financial abuse and has almost no access to whatever my dad earns. i'd like to add that neither of my parents struggle with alcohol or drug abuse. thank you.