Bad Reference

Following a year in a top management position at a new job, I had major health problems requiring hospitalization which affected my work performance. Prior to this position I have had an exemplary 13 year track record. I do not believe this organization or my supervisor will give me a positive reference and I may be terminated. How would you deal with this on a resume or in a job interview? Should I not list this on my resume, and if so, how do I explain the gap?