Does your W know of your DB threads? Would you feel comfortable if she were to read them? I am not saying what you did is wrong or right in reading her diary, but there are things that should remain personal even betwee H and W. I can understand the temptation with it almost calling at you to read it.
I showed my W the DB forums a few days ago, but I told her it was probably best that she not read the thread about us as I speak the truth in them from my point of view and she probably would not like what she reads. As for my W's diary, I could not read it anyway as it is in Thai, but she has shown me several entries in it in the past 9 years where we had arguments. I just had to take her word that we had arguments on those days. I asked her if she ever wrote good things in her diary. Somehow, I think my W used her diary as a means of keeping score of how many times we argued, even though we did not argue that much in our marriage IMHO.
I am just trying to make a point that what a lot of people write in their diaries (and in these threads) is the bad things and they tend to leave out a lot of the good. I think it is just human nature to focus more on the bad than on the good.