Family cat of 20 years dying - What should I do with the last evening I have?

I posted this on catadvice too, and have just copy pasted it over as.

Sorry this post might be a bit of a mess. I got a call from my parents that our family cat is dying, she's almost 20 and we've had her since I was 10 years old. I'm heading back home to see her​ tonight as they were able to arrange to hold things off until tomorrow​.

What things should I do with this final evening I have with her? Photos? Video? I'm bringing her tuna as she always loves it but I'm too much of a wreck to figure out what else I should do now. She's been there for over 2/3rds of my whole life and has never really been sick until now. I don't know how I'm supposed to work tomorrow, all I can do is cry.

I'd massively appreciate any suggestions or advice, sorry it's a downer. I'm sure other people have asked this before but I can't bring myself to search for other answers, i don't even know why.

T​hank you all so much for your time, I just want to give her the best and I don't know what I'll regret not doing.

I love her so much.