A 60-year-old male presents to you at a rural clinic with sudden-onset severe tearing abdominal pain radiating to the back. He has a known abdominal aortic aneurysm of 5.8 cm. His blood pressure is 90/55 mmHg and heart rate is 120 bpm. He is cold and clammy. What is the most likely diagnosis and what is the critical pre-hospital management?