How did Freddie Mercury contract AIDS?

Who gave Freddie Mercury AIDS? Rumor has it Freddie was infected in the mid to late 70’s, essentially on his first visit (or second) visit to New York, which was the epicentre of the GRID (gay-related immune deficiency) epidemic. By 1982 he was starting to show symptoms of being infected already, and by 1984 he had the first appearance of possible KS (Kaposi Sarcoma) on his body, which he thought was bruising to start with, until more started to appear on his body and face - hence the thicker makeup, and la