So I went into a local mom-and-pop camera store in my town (Sam's Camera Exchange in Mt. Kisco) and we tried a filter wrench. When that didn't work, they called their other location and an employee who worked there for quite some time recommended using a rubber band. Having nothing to lose, I put the rubber band on twice and it twisted right off. Without the rubber band, I couldn't get it to budge.

Problem solved!