My Cat Won T Leave My Room

For extra context my roommate had a golden retriever that my cat never met and all of my cats stuff ie.
My cat won t leave my room. When your cat stops freaking out about these things you can leave for a moment and then for short periods of time. The kitten usually stays in one room and sometimes comes out to explore the other parts of the house but runs the back to her room when she sees someone or the other cat. Litterbox food water is in my bedroom to help acclimate her. My 11 year old female cat won t leave the bedroom.
When you come back inside greet your pet and play a little bit. She is kind of scared of my older kitty but has toughened up lately. For extra context my roommate had a golden retriever that my cat never met and all of my cats stuff ie. This can be especially true for cats who have experienced trauma in their lives such as being re homed or abused.
She has been in the bedroom for a whole year. She will hang out with the older kitty in her room but not in any other room. I m afraid she will spend the rest of her life confined to the bedroom and it is breaking my heart. Some cats bond so closely with their humans that being left alone causes the cat to suffer from separation anxiety similar to the stress kids experience when their parents leave home without them.
Litterbox food water is in my bedroom. She absolutely hates the boy cat. I have a 4 year old male and whenever she goes into the living room he chases her back into the bedroom.