Something that doesn't add up (Spoilers)

We're led to believe that the guy in the suit is Adrian all the time because of what Cecilia says, and even after it's revealed it was Tom, she claims it was a one-off and still maintains it was Adrian. In which case:
Why would Adrian want to drive her crazy despite her being the sole beneficiary of his will, and wanting a baby with her? This would suggest that it was Tom all along, with the motivation of him being the benficiary instead once Cecilia was convicted. In which case-
Why would he keep Adrian alive? He could have easily stitched her up as the murderer as seen in the movie. And I can't think of a reason for the brothers should conspire.
So... crap ending?