Confess or Keep Quiet?

Never got along with my mother-n-law, Greta from day one. I dated her son for three years before we finally decided to get married. My father-n-law and I get along well. He is a fine gentle man. He's soft spoken and very polite. I really don't see how he got involved with Greta because they are like night and day. She is forever arguing with him about trivial stuff. One day, she went off about a lint on his new sweater. She went on and on about how he doesn't appreicate anything. Her verbal assault didn't end there. When my husband tried to calm her down, she turned on him.
Well anyway, Greta was recently diagnosed with breast cancer. My father-n-law finally got the nerve to leave her. Their children were devastated  when they learned about it. They felt that his timimg was way off.  My husband  refuses to speak to him. 
On occassion, Me and the children would met with my fahter-n-law at the park or Mcdonald's. He told me that his decision to leave Greta was in part due to a conversation we had had. He said that I made him realize she wasn't worth staying with. He deserved better.  
  I never thought he would go through with, but he did. Now I feel some blame for breaking up their marriage. I'm sure my husband and his sibling would think it was totally my fault. I want to tell my husband before some else does, but I'm afraid.  I am afraid that he may think that I broke up his parent's marriage to get back at his mother. Should I wait or should I tell him before someone else does?From: Afraid w/2nd thoughts