If you kill her, you can never, ever forget about her again. The more humiliating death, the better. Just ties her down, take a couple of poops, couple of pisses on her. Make her swallow some shit. Stab her in the direct front of her throat, deeply, so she drowns on her blood. Will be the most memorable and last several minutes of her life. While she's still warm, roll her over and go to town and feel what it almost must have felt like when there was flowing blood. AT least it will be warm and you have 20 minutes before things stiffen up a bit.