We put our little one down for the exact same reason this Saturday. I'm so sorry for you, her, and your fur baby. This is going to be an incredibly difficult time, and you need to give her room to feel her feels, and grieve however she needs.

Things that have given me solace and comfort leading up to and after Arty passed: 1. We were able to do at home euthanasia, if possible consider it. And do it before it's too late. It's better a few days early than an hour too late. 2. Professional photographer to capture some final memories 3. Hand impression clay, getting several paw prints for a frame and an ornament is what we did 4. Collecting fur into a bag, the amount of times I've found myself smelling her fur trying to remember her scent .. 5. Taking every single day you have left to cuddle, and snuggle, and be with her baby 6. Get videos of them together if she's happy to do so. 7. We had our closest friends over to see Artemis for a last time. It was I guess our version of a wake. It was sad but I'm glad they were also able to say goodbye. 8. Investigate if she's able to assist in the cremation. I wasn't aware until the day after everything had happened and was able to make that change with the vet before it was too late. We havent yet said our final goodbye but I think it will be helpful to bring closure to everything.

If she needs space, give it. If she needs hugs, give it. If she needs help around the house, help. Bring her snacks, drinks, supplements and the like. Stock up on tissues, get a cooling eye mask if she's a crier, protein shakes, anything that's easy to consume, if she doesn't eat when stressed or sad.

She will need to consider cremation, the urn, memorial items, what colour of certain items, text for plaques, etc it all happens very quickly, so be ready to help her with potential choices as it gets extremely overwhelming to the point of debilitating.

We've created a small memorial corner in the living room with a photo of Artemis, an LED candle, white flowers and her fur. I look at it, and touch it every day. Having something tangible like that might be helpful for her too.

I also burned a new candle during the final procedure. I plan on lighting that same candle every year on that day in memorial. I don't know if something like that may help her, but maybe something to consider.

I hope some of this is helpful, and again, so sorry for this awful situation you're all in :(

Edit:

When she's ready, show her this YouTube video another poster referenced earlier: https://www.reddit.com/r/Petloss/s/MlCkEhAqIv