Help my relationship

I have a fiancé and 3 of her kids that I support and live with me. She is extremely abusive verbally and talks with the foulest language imaginable, both to me and hers kids when she freaks out. In fact two of her other kids live with her mother because they can not coexist in a house with her. They fight and threaten to kill each other. She now wants to leave, and I am done dealing with her at this point but I don’t know what to do about the kids because I know they will have a horrible life. She has an 8th grade education, had an arrest warrant when I met her( which I paid to take care of for her) owes over $20,000 to the IRS because basically she is ignorant and at the same time irresponsible and didn’t take care of her problems. What should I do?

Have you ever spoken to the children and find out what they want?? They matter too