If you escape from her, you sacrifice other life, so why not you kill yourself again? You're a fragile baby, moreover you can use magic, float yourself and fall head first to the stone or something pointy and hard, i know it's depressing but still better than live with her
Because the title, i expect the sister always found mc whatever he did to run from her, so chance to this manga have good ending is close to zero, if anybody have a spoiler can you tell me