The actor-director shared on Instagram on Thursday, October 28, that the three-year-old Persian cat has passed away due to a type of leukemia and a strong bacterial infection.
"My heart is shattered," he wrote in his post, which showed a series of photos of Mandy. "I miss you so much already, Mandy."
"You were always there for me when I needed comfort. You knew exactly how to make me smile with your warm cuddles and kisses every night. You were the first to greet me in the morning and the last one to say goodnight. Hay."
Khalil said he regrets not being able to say goodbye to Mandy, as he admitted that her death was "all too sudden" for him.
"Thank you Mandy," he then said. "I will forever cherish our memories together. I love you."
In light of Mandy's passing, Khalil shared pictures and a clip of himself with his beloved pet cat, along with the heartwarming caption, "See you on the other side, Mandy."
Khalil's girlfriend, actress Gabbi Garcia, was among those who reacted to his post.
"Ily," she wrote, along with sad face, red heart, and folded hands emojis.
Others were Angelica Panganiban, Janella Salvador, Ria Atayde, Rocco Nacino, Patrick Sugui, and Aeriel Garcia.
In his post, the former Kapamilya actor also left an important piece of advice for fellow cat owners.
"Please make extra efforts in understanding the body language of your fur babies," he said. "We never knew that Mandy was going through pain cause she was so so good at hiding it. She was playful, her appetite was okay, she was normal. One morning, hindi nalang siya makalakad and 24 hours later, we lost her."
"Vet visits are really important," he added.