05/20/2014 at 02:05 PM EDT
made his first public appearance since nearly dying
from drinking too much alcohol.
The 34-year-old Canadian rocker was photographed looking frail while walking around Los Angeles on Monday with the help of his fianceé Jocelyn Aguilar and an unidentified woman – just days after revealing the battle with alcoholism that landed him in intensive care.
Whibley, the lead vocalist of Sum 41
and ex-husband of Avril Lavigne
, posted a heartrending message
to fans on his website Friday, explaining why he spent a month in the hospital.
"The reason I got so sick is from all the hard boozing I've been doing over the years. It finally caught up to me. I was drinking hard every day. Until one night," he wrote, "I was sitting at home, poured myself another drink around midnight and was about to watch a movie when all of a sudden I didn't feel so good. I then collapsed to the ground unconscious."
Whibley was "stuck [with] needles and i.v.'s all over," sedated for an entire week before waking up to see his parents standing over him, he said. He has vowed to stay sober and is inspired to get back into the studio and on tour.
"My liver and kidney's collapsed on me. Needless to say it scared me straight. I finally realized I can't drink anymore. If i have one drink the doc's say i will die," he wrote. "Anyway i have my passion and inspiration back for writing music."