If I remember the particulars right, Kahlest was a servant/maid/babysitter in the House of Mogh. Her honor was inexorably tied to that of the House of Mogh. When the family of Mogh was dishonored so too did everyone associated with that house suffer dishonor.
After Khitomer, Kahlest was a single woman with little or honor to her name. Her master's house was for all intents destroyed. Both sons of Mogh were children, one was with humans and the other hidden. Neither would be in a position to attempt to restore or gain honor for their family until she was very old. Kahlest's family was probably of little to no importance, otherwise she wouldn't have been with the Mohgs on Khitomer. Thus, having very little honor of her own and also suffering the stigma of dishonor associated with Mogh she became a pariah, an honor-less Klingon with no real way to gain honor.
Therefore, she wanted to die. Of course, she couldn't commit suicide as that would bring her more dishonor, and apparently no one considered her worthy enough to murder. So she subsisted, merely living but not really alive.