u/CantThinkOfOne2323

As the title says how can I help my 13 year old cat grieve the loss of his biological 14 year old brother? We had to unfortunately euthanize my cat yesterday as he was getting super sick and quality of life was decreasing. I did not take the younger one with me to euthanize him so he does not know what happened and I feel like I handled that poorly because I seen online that now he will be “waiting for him to come home”. How can I help him not be lonely and get through this?