How Can HIV Infection Be Diagnosed?

My husband is not sure if he have hiv. He confess that he was so drunk and not sure if he did drugs in a party. I ask if he inject drug or took it orally . He can t remember at all. Do you think he had sex because he now uses condom since his confession. He won t go to doctor to check. He get upset if I mention why do we need to use condom. Which he never use it before. I don t understand because he knows after he confess I visit my genacologist and I took hiv test and it was negative. So why he demand to use condom.