how and why

my exboyfriend cheated on me, with a female and tried to make me feel as though I done something wrong when I knew I did nothing but be there for him. we have a 6 year age difference but I thought he was someone I should give a chance. anyway. he is still with this girl and when I talked to him he told me that he didnt want to let me go. but when I go to call him just to see how he is doing he doesnt either want to answer my phone calls or will tell me that he is busy. question, how can you cheat on someone and then turn around and say that you dont want to let that person go, but at the same time ignore them. is there anyone out there that can tell me something.