Spouse should tell each other of their pasts
I believe a relationship should be based on trust and truth. So a couple should share their past with each other and allow your partner to decide whether he or she would want to stay in the relationship. You should not tell everything in the early stage of the relationship, but as the relationship becomes older and the couple is thinking of spending the rest of their lives together, they should open up to each other about their past and in that way they will have a stronger relationship.
Some people would agree with you and some would not. This counsellor believes that there are some things a spouse should take to his or her grave and never divulge. I know some people will disagree, but that is how I see it. If a spouse can be absolutely certain that his or her marriage will not be ruined, but strengthened, he or she may say something. However, it is extremely risky to just talk about your past. He or she may be throwing away his or her life. We are living in a very crazy world and common sense must always be exercised.