I gues it is a very hard decision for both the people involved.
One thing I would like to ask you is have you in your heart of hearts tried everything humanly possible to save this marriage with the tools that you possess?
Have you turned every rock to try to find a wa resolve it.
If walking out that door donot affect you with a feeling that takes over you too strongly then I would think that you are ready…if not then there may be some work that may need to be done on your part.
I hope what happens , happens for the best.