Mother overthinks, blabbers all the time

My mother faced lot of problems in her life.Her father died early leaving them with less money.after her marriage,my father use to beat her & have had extra marital affairs as well.he always wanted a son so she conceived multiple times.out of 5 pregnancies,there were 2 abortions & 1 miscarriage-since it was me & my sister, he never liked us & spoke ill with her about how girls should never be trusted, shouldn't go out,hang out,should be married etc.my parents separated in 2009,there was no divorce but he just left without any financial support.it was a struggle but some how we’re able to make ends meet.My mother changed during this time,she stopped eat properly,do fasts 2-3 days a week or for a month,not wear clothes properly.If asked why,she will shout and get angry.speak I'll about me coz I work in US shift.Even if we do something good/buy her something,she will not accept and blabbers all the time, doesn't sleep properly,wakes at least 2-3 times, has sudden mood swings. What to do?