You know, that's a really good question and one that I've gotten several times in the past few months. I hardly remember the fear now, so long after the successful second round, so it may be heartening to know that it's just temporary.

There are so many variables in the process (e.g., available spots, faculty status, financial issues, etc.), I think it's most important for you to focus on those things you can control and learn as much about those that you can't. Craft a more attractive application, engender personal contacts with faculty and students, interact with your references for ideas and support, deepen your knowledge of the field, rewrite your essay using outside critique... in short, be true to your interest in the field.

Though the idea of rejection is paralyzing, your enthusiasm for the field should be energizing. Know as well that you have other options in life and that your path isn't going to be set in stone by this one decision. For instance, while I find it hard to imagine my life without having gone to grad school, my life now is only tangentially related to what I thought I would be doing. Could I still have been a teacher and historian (as I am now) without this experience? Absolutely. So did my life change unalterably? Superficially, sure, but perhaps not as dramatically as I might otherwise have thought.

Obviously I can make you give up the paralysis, but if you think more about the things you can do and draw from your excitement about the field, you'll find the process far more enjoyable and successful than fear would allow.