SunLife said my condition is more mental than physical (it's not) and said I've have to take a lump sum

Sun life just called and informed me that my situation is more mental then physical. They told me that I should take a lump sum (about 3 months) If not, when I am approved for social security I will have to pay all of the money back to Sun Life $48,000. I suffer from Rheumatoid Arthritis, Migraines everyday, Fluoroscopic guided spinal facet blocks for my spine. I had gastric bypass surgery in 2006 and am now having nutritional problems, I have tingling in my feet and can no longer sit at a desk for more then 10 minutes at a time. I take Welbutrin 150mg, Wellbutrin 300mg, Ativan, Tylenol 3, Imetrex , Topamax Depocote. I have worked all of my life. I am 54 10 months female with no formal education. I do not know what to do. Maybe you can help me. Sincerely