My best friend is leaving this world on Sunday and I'm devastated. Any suggestions on things to do before he passes?

My little man here is 14 years old and is suffering from some aggressive lung cancer. I rescued him when he was just 5 months old.

I love him with my whole heart and will miss him so so much but I know it's the right call to make. I just want to do all I can to enjoy what time I have left with him.