<human>: Could you distill the essence of the text into 1-3 sentences?

(Names have been changed to protect the innocent)
My best friend, Sally, and I have been friends for quite a long time. I spend time with her and her family a lot, we are all close. Recently we all learned that Sally's family and I have a mutual friend, Ruth. Ruth is one of  the counselors at my church who I am close with, and Ruth has been friends with Sally's family for a long time, and babysat Sally when she was little.

Today I was talking with Ruth and we mentioned the fact that we both know Sally and her family. Ruth was telling me about how she had babysat Sally when she was a baby, etc etc etc... *Then she accidentally told me that Sally had been adopted as a newborn by Sally's parents.* Ruth assumed that I knew this, however I had not known this, and after discussing it further we came to the conclusion that we were pretty sure that Sally does not know she is adopted. Ruth and I then decided to bury the topic and lock the topic away and never bring it up again.

I know that I can never bring this topic up with Sally or her parents. That could be disastrous. Sally had a sister who is nearly 10 years older than her, and her parents are both in their 60's. (Sally is 16.) I have no clue as to weather or not her sister is biological.

I really wish I had never found this out. I don't feel like I will be able to bury this secret; that is not to say that I will have a problem keeping it a secret, its just wearing me down. *How do I not let this bother me anymore??
<bot>: I found out from a mutual friend that my friend is adopted. Mutual friend and I are pretty sure friend does not know she is adopted. How do I deal with carrying this secret, and not let it bother me?