It went totally not according to plan. I called the department of Graduate Studies to ask how to proceed. They gave me directions but followed up with an email, cc'ing my program. The program coordinator instantly responded with severe concern, and I explained my personal situation. She asked me to let her know ASAP what I was doing. This occurred around 4:00 pm so I slept on it. The next morning, she reached out to me again, stating that the program head "needed a decision." I composed a formal/business letter stating my gratitude for the acceptance, reason for withdrawing, and wished that if the course of events dictate, we may meet again on pleasant terms. I cc'd the graduate studies department and he was the only person to confirm receipt of the message. I haven't heard from them since. I hope someone on the waitlist was able to receive my spot.