I just came out of a tough Major Life Situation myself. The rationality 'tools' I used were mostly directed at forcing myself to be honest with myself, confronting the facts, not privileging certain decisions over others, recognizing when I was becoming emotional (and more importantly recognizing when my emotions were affecting my judgement), tracking my preferred choice over time and noticing correlations with my mood and pertinent events.

Overall, less like decision theory and more like a science: trying to cut away confounding factors to discover my true desire. Of course, sometimes knowing your desires isn't sufficient to take action, but I find that for many personal choices it is (or at least is enough to reduce the decision theory component to something much more manageable).