CS
I, like the others, won't presume to speak to the particulars of your marriage, but I agree with Laura, if you are able to step away from you situation and try and look at it objectively you may find you are better off than you would have been had your wife stayed. You said in your post that you knew she was going to leave even before you were diagnosed. I expect the effort it took on your part to try and prevent what you felt was inevitible, may have cost you far more than you realize.

There are worse things than being alone, being treatedly badly is one of them. I worked in the field of divorce for many years and saw too many people try and hold on to a dead marriage by their bloody fingernails, for the children, out of fear of being alone, or fear of financial ruin. The toll it took was far worse than it would have been if they had spent that time building a new life.

I really have no qualification to give advice or even comment, but I believe if your wife had stayed she would still have been the same woman who left you (which doesn't really make her a very nice person) only on top of that she would be where she didn't want to be.

Her leaving or staying was out of your control, but what you do with the rest of your life is not. Don't let one tragic happening determine your course from here on out.

Keep your chin up.
Pam