Welcome to PT. I'm so sorry to hear this. It sounds like Gabbie feels like the new cat is a threat to her. I would try using some Feliway/Comfort Zone plugins to see if this will help calm her down. You can buy them through your vet, online, or at most pet stores. You can also buy the spray so that you can use it in certain areas.
I don't think that moving her food, water, and litterbox to another area is a good idea at this time. I would leave it all in your bedroom until she's much calmer. You just have to let Gabbie take the time that she needs to get used to the other cat and feel more secure in her home. You may also want to contact an animal behaviorist for better information. I've never had this problem but my cat Ziggy is also a scaredy cat with strangers and she'll hide and won't let any one except my roommate and I see her. Good luck.