I just received permission to defer admission one year from the school I plan to attend in order to save some more $$ before moving and going to school. Defering a year, especially if you can live with parents or otherwise keep living costs low, might be a good plan. Also, you could apply to some in-state schools w/cheaper tuition. I would re-think paying top dollar for a school that you are not really excited about unless you have no other options.
That said, if a top dollar school does interest you, I say borrow away, even if you are planning on a public interest career. You need to follow what you want to do. Would you rather make $1500/mo debt payments, live cheap, but be doing work you care about, or grind through work you don't like but be debt free? I've been in situation #2 for the past few years, and being debt free is a small consolation for the nagging feeling that I am wasting my time, talents and energy.
You have a chance to pursue a career you are passionate about. That is a great opportunity! (I'm not trying to downplay your anxiety, frustration or disappointment here, I am just trying to give you a pep talk.) HTH...