@snarlatron @momofsenior1 You are NOT officially required (at least by law) to attend a school that admitted you via Early Decision. You can cite your financial aid package, among other reasons, as a reason for declining an offer of admission from your ED school.
I would personally choose to take out loans and pay full tuition for Northwestern over a full ride from Loyola, but it all depends on what your career goals are and your family’s financial situation. Wait to see what aid package Northwestern offers you (if you get in) before making your decision.