Can our brief separation be considered a divorce?

My husband and I were married in January 1964. Our daughter was born in September 1964. My husband and I briefly separated in 1967 and then reconciled in 1968. He died in 1968. I have received a survivor's benefit from Canada Pension, and now I just recently retired. Canada Pension has just told me that they have been "overpaying" me because my husband and I were divorced. We were not divorced. Can our brief separation be considered a divorce? I am puzzled as to how CPP came to this conclusion. They are saying this will affect the amount of pension I receive from my own pension that I have been paying into since 1967. I can prove we were not divorced.