I cannot actually write the diary entry for you, but I hope these ideas will help you.
In my opinion, Mary Maloney's entry would not show any great amount of guilt. I think that we can see this from how calmly she gets rid of the leg of lamb and from the fact that she starts to giggle at the end of the story. I think she feels that her husband deserved what he got.
You could also argue, though, that she will sort of break down once she gets over the initial need to get away with the crime. You can argue that her giggling shows that she is starting to do this. After all, she has had a huge shock and must be emotionally drained.
weres the answer