You ' re not obligated to protect your adult sister or take on more abuse from your mother because you ' re used to it . I know your sister isn ' t asking that of you , but this shouldn ' t be an obligation you feel you should have . You can support your sister and offer advice for how you dealt with it all these years , but what she does with it is her choice . I had fairly similar experiences with my mom growing up as you did difference was I was actually overweight PCOS in a family of naturally fit to averagesized people , which encouraged my mom to project her body issues onto me on a near constant basis . I still deal with a warped perception of how I look regardless of being within my normal body weight , but managed to work through the worst of it . I have very specific boundaries I ' ve set with her because of this which keeps things complacent . It ' s better not to invite her scope back onto you when it ' s not likely she ' ll understand the consequences of her actions even with limited contact with her grandkids . Don ' t invite that kind of negativity into your life when there will be little reward .