Feel bad keeping them seperate

Hello everyone...new to this so bear with me please...I have 2 female cats both about 3 yrs old. I got an 8 moth old female kitten yesterday. I read all the posts about keeping them seperate. I feel bad tho with the 8 month old. In a new home and now stuck in a room by herself. She hisses and growls whenever the 2 other cats see her so I keep the door shut now. Any words of wisdom to help me not feel so bad about keeping her contained for a week or longer..got a big heart I guess..

Don't feel bad. In actuality, when cats are introduced to a new place, smaller spaces are actually comforting to them. Having run of the full house can be overwhelming.

Just spend as much time with her as you can while the cats get used to the idea of other cats being in the same space and bond with her. She'll be fine.

She will get used to things. Good for you for keeping them seperate!