My suggestions would be to close her in the room like you did in the beginning and not let the cats interact. Spend plenty of time with the new cat until she's comfortable comming out of the cupboards and is acting more like the cat you fell in love with.

Once that finally happens (it may take days or weeks), then start the introduction process over again properly. Use the Feliway plug in's to help minimize stress.

Try also taking a cloth and wiping it over the old cats then wiping it on the new cat, and back again, so they can get each other's smells on them. If that goes well try feeding the new cat right at the door so she can smell the other cats but know it's ok and they can't hurt her.

Once she's ok with that, shut in the two old cats in a room, and leave the door open to the new cat's room. Let her come out when she wants to, don't force it. If after a few hours she doesn't try to come out, shut the door, let out the other cats and try again the next day.

If she does come out, let her explore at her own pace and get her smells around the house for the other kitties to smell.

If that starts going ok, then you can try SHORT supervised introductions face to face. There are several ways to do that, one is to let one old kitty at a time into the new kitty's room, OR put an old kitty in a carrier and set it in the new kitty's room for a short time gradually increasing the time if things are going well. This would show the new kitty that she doesn't have to fear the old kitty's, at least on her turf (her room).

I've used both ways depending on the cat. In my case, starting from scratch that way, it sometimes took up to 2 months to make proper introductions, and at that I still have some cats that just will not get along no matter what. There are no guarantees, however these steps (and more that other people can add) should give you the best chance of having the cats at least tolerate each other.

Good luck.