Should I continue keeping my parents' (they cheated on each other long ago) secret to myself?

I already know (through dad's abandoned journal) my parents cheated on each other long ago. Mom cheated in 1992 when they were boyfriend and girlfriend. Dad's revenge cheating took place in 2000 (though they were married by then and I was just 2 years old) and apparently they've worked on their issues long ago. My twin sisters and I grew up thinking it was a perfect family. Never knew that sordid detail.

By Aug they'll be 27 years married. I haven't told anyone that, not even my own parents, sistera nor husband; no one. Everyone in the family and friends have a great image about my parents. Normally I hate keeping secrets in a marriage but is this the one secret I have to forever keep to myself?

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If I were to reveal what I know, their image would plummet, esp mom's because her cheating at the time was worse.. yet she was forgiven. Dad didn't rat her out to his parents nor friends nor anyone when it happened and mom didn't tell anyone about his brief revenge affair. That's why both of my parents get along with both sets of our grandparents. My parents kept that to themselves. I'm the only one that knows what happened.
Should I continue keeping my parents' (they cheated on each other long ago) secret to myself?
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