I watched my brother attempt when we were younger. He promised he'd never attempt after seeing my severe depression when my best friend successfully committed suicide...
I know it sounds crazy, but I sat down with him recently and discussed potential suicide together. He made it quite clear that even though he's on disability for life, can't walk for more than fifteen minutes a day, has multiple mental illnesses, and lives a life of solitude (I'm talking only seeing me throughout several years of lying in bed all day and all night by himself)... He would never attempt suicide and that he does not accept my choice to CTB.... he has, seemingly, nothing to live for but still refuses to accept an "easy out".
Perhaps sit down with her and have a serious discussion of why you want to and if she wants to?