Tried introducing new cat to older cats. Yikes. How to proceed?

So I adopted a young female (spayed) this past Saturday. She's been in my spare bedroom since then. I have 4 other cats; 3 females (all spayed; ages 13, yrs, 12 yrs, 11 yrs) and 1 neutered male (almost 2 yrs).

On Sunday while I was going into the new cat's "room", I didn't close the door fast enough and she saw my male cat walking by. She chased him through the house like a bat out of hell; it ended with her almost cornering him, fur on her back standing up, tailed fluffed...he just sat there kind of dumbfounded, I think. I scooped her up and back to her room.

Last night I brought her downstairs into the living room in her carrier; so that the other cats could see and sniff her. None of my females seemed to care, even my male Hobee didn't though he seemed a little uneasy (think she scared him! LOL). I then put Hobee into the basement and let the new cat (Bitsy) roam around upstairs. One of my females just rubbed noses with her, no issues. Another of my females didn't seem interested. My other female was watching Bitsy like a hawk; I sensed there could be trouble so watched them closely. After about a half hour I put Bitsy back in her room.

Tonight I decided to keep Hobee out and let Bitsy out of her room, but watching very closely. My 'cautious female' from last night gave her a swat, Bitsy hissed. Cleo (the one who initially rubbed noses with her), not a problem. Bitsy did chase Hobee down into the basement (God she's a brave little spitfire; she's about half the size/weight of my other cats).

After about an hour, I saw Bitsy chasing poor Spookie (the one who last night didn't seem to care) up from the basement, both of them going a million miles an hour. She chased Spookie up on a scratching post; both of them hissing, Spookie clearly mortified (she's generally a skittish cat, even after 11 yrs of having her). Spookie sounded a little snuffly; she gets like that when very stressed (like when she's at the Vet).....not wheezing, just sounds nasally snuffly, breathing a little faster. I immediately locked up Bitsy in her room, enough for tonight.

Now how do I proceed? I don't want Spookie to be mortified of her. I don't want anyone to start spraying (God forbid). I don't want my existing cats to be terrified of this newcomer, that's unfair to them. She's a real little feisty girl, obviously.....is not afraid to chase someone and corner them.

Should I take a break for a few days, just leave her locked up in the evenings (of course she will be locked up during the day) for a couple of nights, maybe even until the weekend? or is it best to just keep doing this every evening until everyone starts to become more used to each other?

Would appreciate your thoughts.

Thanks
Lisa

Well throughout the week, when home from work, I'd let her out for a bit. My 3 females are now used to her. She was even eating off the same bit plate they eat off of for dinner this evening (feeding time at the zoo!). So we're good there........but she's terrorizing my poor male Hobee and I don't know what to do.

I've had her out of her room for most of the day, a few hours now. He's been hiding out in my clothes closet. When she sees him she runs at him, a million miles and hour. He's a very docile cat, very good with my other cats, was from the minute I brought him home from the Humane Society; he's so good with other cats that while at the H.S., he was housed in a section called "Mewtopia" -- it's a large area where 8-9 very friendly/sociable cats are kept together.

He's afraid to come downstairs. I caught him down in the basement, I was talking to him; she came downstairs saw him and charged for him.............he was terrified, running, and when he runs she chases him.........I'm screaming "STOP" because I'm terrified someone's going to tear out someone's eyes. I think with her, part of it is "fun" and part of it isn't. His mistake is to "run" because then she chases him. He's twice her size. I'm terrified he'll start spraying or something.

He's currently down in the basement by himself; I put some food and water down there, it's pretty nice down there.........but I feel bad for him. I don't want him to feel threatened or isolated because of her.

Any suggestions?

I put Bitsy in her room for a couple of hours, to give poor Hobee a break. I just let her out, she hates being locked up. I brought her downstairs and the minute she saw him she made a bee-line for him and chased him up stairs; I found him sitting on top of my nightstand, hissing; she went under the bed but then came out from under it and tried to jump up on the nightstand, he was mortified. This is killing me! I don't know what to do and I don't know where to turn. If someone starts spraying, somebody's going to have to go and that will be the new cat.

Will they ever get along? What can I do to foster it?

She just has a thing for him, I don't know what it is. From the first time she saw him she went running for him.

This isn't fair to him at all. He shouldn't have to hide or cower or be chased.

I wish someone here had some suggestions