my babys not eating

Well, stopping eating is serious stuff, especially for an 8 year old.
First thing you need to do is, no matter what, get your kitty to eat, immediately, like right now...
You can warm up her wet food a bit, and if she is not eating at all, put a little on your finger, then on the roof of her mouth. Give her some tuna, or boiled chicken, or baby food (no garlic, no onion).
Since she is 8 years old, a trip to the vet is in order ASAP too, in my opinion; I would get a full senior panel done.
Make sure the cats have a peaceful place to eat and to be away from the puppy - that includes litter boxes - believe me, it will save you a lot of headaches.
You might want to keep the puppy away with a baby gate while the cats are eating on a schedule.
No matter what you do, get your cat eating ASAP.
I am sorry if I sound a bit dramatic, but a very serious disease can result in just a few days of not eating (hepatic lipidosis, fatty liver disease), and that it can be deadly. I rather be dramatic than see you with a very sick kitty...
There is a food that is called Fancy Feast that cat LOVE it. Most places sell it - the seafood variety are the most popular... I would strongly advise to get some.
No matter what you do, don't just let it up to her; make sure to personally get her back eating.

Definitely. Even if you have to force feed her. What I do is take some wet food (use the kind that comes out the shape of the can, not the kind with chunks in gravy) and mix in a little KMR (the liquid, not the powder) just enough to soften it up a bit. Water can also be used, but KMR has lots of extra fat and calories. Put it in a blender or food processer until the mixture is a thick liquid. Heat it up a little, no more than you would formula for a baby. It can then be administered with a syringe. Sometimes messy, but so worth it. Carolina Lima is right, if she doesn't eat soon she can and WILL get very sick. Fatty liver is almost impossible to reverse. It has happened but I hear very few stories with happy endings where this is concerned. Get her to a vet ASAP and if she won't eat on her own, force feed her in the meantime. The vet may have to keep her and put her on IVs. I had this happen to one of my kitties in August and he did not survive. It is likely the stress causing her to not eat but it is incredibly important to keep food in her until you can get her to a vet, rule out other causes and address the problem. Her liver can't shut down if it is continuously processing food. Be careful not to overfeed her though. I know how much she should be fed is based on her weight but I'm not sure exactly what the amounts are. Hopefully someone else on here knows, in case you do have to resort to force feeding.

I truly hope all turns out well for you and kitty.

It seems the consensus out there is 150 calories a day will keep an average adult cat safe from HL. So, I would aim for at least 150 calories...