I think Delia has put up with her husband for so long because she doesn't know any other way to live. Ever since she married him, he has been beating her and after awhile, she began to familiarize it with her husband. Also, being a God-fearing woman, she does not want to divorce her husband because that is a sin in her book so she continues to put up with her husband. However she reaches her limit when he begins to threaten her home, which is what she worked her entire life for. Instead of giving in to his demands which is what she normally does, she stands up to him because her home is the one thing that matters to her in her life and she will not abide by him any longer. Delia puts up with him because she does in a way love him, regardless of how he is. I believe it's called battered woman's syndrome, Delia has been abused by him ever since she got married to him. Usually she just ignored his anger but when she decides not to save him I think she's just thinking good riddance.
I hope this helps you out!
