How Can HIV Infection Transmission Be Confirmed?

Hi I am an Albanian, I have a love history that is very complicated. my ex boyfriend who lives far from me told me that has a pancreatic cancer and I was ready to help him but now I have doubt that I had to do with a drug dealer. He is 25 years old. He told me that he had understood that he was ill 4 years ago. He also told me that the doctors told him the he had a familiar history of cancer. His father had died when he was 47 years old from this illness and doctors told him that he will live like his father. He smokes, drinks alcholol and he told me that take marijuana. His had lost weight, couldnt sleep, but was eating well, after eating had vomiting, sometimes told me the he couldnt see the light. He told me that I mnot afraid from death because I dont have what to loose. for 1 week he was only with me and was only smoking.Can a person who takes heroin stay for one week without taking it? Please inform me and help me to find the truth because if he was using heroin and I wasnt knowing I may be infected with AIDS. I am very scared and I need to know the truth.