I watched one of my best friends in the world go through this with her husband, and it nearly ruined their otherwise (ridiculously, annoyingly good) relationship. Same exact scenario as above, with him eventually saying that they needed to get rid of it, and her dragging her feet because she cared for the cat and, I would presume, women form those attachments a little easier, whether because of the strong maternal instinct or just a more general sense of empathy. Regardless, if retraining the cat doesn't work, your best bet is to get rid of it, grieve for both the cat and your less innocent conscience, and move on. Animals are wonderful, and we have a responsibility to them if we choose to obtain them, but that responsibility - like all responsibility - is not necessarily infinite. It sounds as though you're attempting to do the responsible thing, which is commendable, but if keeping the cat continues to impact you negatively, ruin the things you've accumulated and care for, and perhaps creates an unsanitary living space, you'll need to get rid of it, and then get over it.