I can't believe I am typing this, my sister and I have found out my Dad is having an affair - He doesn't know we know at present. My Mum has been borderline personaility disorder, but she has been stable for a while now, with peaks and troughs now and again as to be expected. If I tell her, I am worried she will not be able to cope with this and I am worried what she may do. It would destroy her but equally I am worried her reaction would be extreme. On the other hand if I don't confront my Dad and tell my Mum then I wouldn't feel comfortbale withholding this information. Any advice would be appreciated. What would you do in my situation?