A recent edition of New Scientist (see www.newscientist.com) had an article about the "sunk-cost fallacy" in which we tell ourselves "I've sunk so much investment in this, I have to keep going." Apparently animals are not dumb enough to fall for this.
Take my advice, don't be dumber than a dumb animal, cut your losses and get some cognitive-behavioural training. It's fast, cheap and effective (and that's only the training!) and it'll feel like coming out of a stuffy room and into the fresh air. Never mind the "cookbook" jibes - that's sour grapes from people who didn't have the sense to jump a sinking ship!
For a good CBT training course, visit www.chester.ac.uk