A 57 year old women with chronic lymphocytic leukemia has a 2 week history of increasing malaise, decreased exercise tolerance, and darkened urine. Her CLL was last treated 2 month ago with chemotherapy. On examination, she has jaundice. Temperature 37.3 C, BP 142/82 mmHg, HR 117/min. splenomegaly is present. Hemoglobin 6.9 g/dl Total bilirubin 6.3 mg/dL Leukocyte count 6500/ul Direct bilirubin 0.5 mg/dL Platelet count 250,000/ul Lactate 457 U/L dehydrogenase Reticulocyte 10% of Direct Positive for IgG count erythrocytes antiglobulin (coombs) test Which of the following is the most likely diagnosis?