Well, I mentioned in a different response that we are not Catholic. So.....
However, I also mentioned that my father stayed in the marriage because he felt divorce was wrong, BUT also because it was his duty to protect us kids to the best of his ability and there was no way the courts in those days would have allowed him custody. Divorce would have been a far greater disaster than the marriage was for us as children - although that was difficult to understand at that time.
It is often the mother who is problematic. We cannot know what abusive mothers went through which warped them so decidedly. I am sorry that you dear brother was unable to deal with the pain, I am happy that you are as whole and happy as you can be.