The 56-year-old singer's Wham! bandmate - who passed away in December 2016 from heart and liver problems - confided in him about his sexuality in 1983, and while the 'Careless Whisper' singer was concerned coming out publicly would end his dreams of competing with major stars such as Michael Jackson and Madonna, Andrew had other fears.
Andrew wrote in his new book 'Wham!: George & Me': "A terrible additional worry was the emergence of AIDS.
"I know I wasn't the only friend of George's who worried about him during that uncertain, frightening period."
Andrew recalled the moment George confided in him about his sexuality, which came after they finished filming their 'Club Tropicana' video at Pike's Hotel, Ibiza.
George asked his friend to come to his room, where he also found their backing singer, Shirlie Holliman.
He recalled in an extract from book published by The Sun: "When I walked across the hallway to George's room, Shirlie was already there, perched on a large sofa in the suite. George was still in bed. He smiled as I came in.
"The mood in the room was so relaxed and familiar, yet what George was about to reveal was clearly a big deal for him.
"'I didn't know whether to tell you this', he said, looking across at Shirlie. But I'm going to. I'm gay'."
Andrew later learned that George had already confided in Shirlie - who is married to Spandau Ballet's Martin Kemp - and was worried about telling his bandmate, but she reassured him that he wouldn't care.
Andrew admitted he was surprised but only wanted his friend to be happy and his confession made him realise why his pal had never had a serious girlfriend.
