I am really losing it. DD (17) has lots of problems (MH/substance abuse etc) and all my time and energy completely exhausted losing sleep and sanity. A&E, SS etc involved with DD no.1 and lot of tears etc etc.. so in a way no wonder she is acting like this, now DD no. 2 (12) started really playing up. Only up to two weeks ago she was an angel. But now challenging every single word I say. She is constantly using FB, checks her mobiles. I feel like such a crap mum. I should keep my cool, but she is driving me mad! Other mums, how do you keep everything under control and remain calm with other chid(ren) when/if you have a difficult DC?