Doesnt look like she "going" anywhere, to me it looks like shes about to slit her wrists...annd thats about it. Perhaps cry harder from the pain she inflected upon herself.
If she slices horizontal Tsukasa would only hurt herself. The wound wouldn't be large enough to cause death by blood loss. She would heal eventually. But if she slices vertical, all the way down her front arm, then its another story...