What did Margaret do?

Margaret Macomber is Francis Macomber's wife in the short story "The Short Happy Life of Francis Macomber" by Ernest Hemingway. At the end, after Francis' discovery about himself, he is shooting at a buffalo that charged at him only to die when Margaret shot "at the buffalo" and instead hit Francis at the base of his head connecting to his spine. She claims that she had hit him by accident when aiming at the buffalo. However, I think that she was only telling a partial truth. She probably killed him by a mix of her unconscious desire to kill him to stop him leaving her and her desire to shoot the buffalo. I believe this because if she just wanted her husband to die she would have left him for the buffalo to kill. At the same time though the buffalo is a far larger target, so even without a lot of training with the gun she would have been now likely to hit some part of the buffalo instead of a small part on her husband's body. This is why I believe that Margaret Macomber killed her husband, Francis Macomber, because of her unconscious decision to stop her husband from leaving her and her desire to not allow the buffalo to kill him.