First, sorry for the loss of your first wife. It is clear that you truly appreciate the nature of your first wife even in death. Moving on from a deceased spouse can be difficult for some people as they tend to compare the present partner with the deceased.
Yes, it could be true that your wife is just a moody person with a bitter personality, but you should never compare her with your late wife. Separate the two and allow the current relationship to grow and survive its own life. If you truly believe that your new wife is incapable of changing, then divorce might be an option. Try professional counselling and if you still feel like divorce is a solution, follow your heart.
All the best