As a matter of fact, CoCo, the question of why our mother stayed with dad during all those years we children were being terrorized has been discussed among we three siblings. (My younger sister, BeksBks, came along in 1960 and she endured the same home life as I describe above.) Seems like a lame excuse for her to simply say, "because I loved him". I believe there was an unhealthy streak of the 'martyr complex' that she was drawn to. I should mention that there was always the couple of days following one his binges when he was contrite and miserable. This put her in the position of being the forgiving loving caregiver. It was a sick situation in many ways.
There was also her support from the family. After all, she didn't have grounds for divorce. Sick.