Sucks for LW but the best option now is to come clean. It would be unfair to remain silent and allow her family members to continue suspecting one another of having affairs.

Curiously absent from the letter is the reason LW and her aunt kept the adoption a secret from LW's family or what LW thinks (or thought) her parents' reaction would have been. Was it just social stigma or is there a toxic family dynamic at play? The answer to this question could change my response.