Lost my 6 year old cat unexpectedly & am so incredibly sad.

my husband and i had to put down my 6 year old orange boy tonight due to his kidneys failing and i couldn’t be sadder. i held him in my arms until the last second and now i cannot get the image of him passing away out of my head. i know this will all take time but i just feel heartbroken. i have two other cats (one being his brother) and i feel so bad that they don’t know what happened to him. has anyone been through this and have any recommendations for my other cats? unfortunately it was all so unexpected that they didn’t get to see his body or say goodbye properly. ❤️‍🩹