MY CAT IS ATTACKING MY OTHER CAT AND DOG,WHAT DO I DO WITH HER ?

MY CAT HAS BECOME VERY MEAN SHE ATTACKS MY BLACK LAB AND ALSO HAS BEEN ATTACKING MY OTHER CAT SHE WONT LET HER EAT AND IS BITING HER.I LOVE HER TO DEATH BUT SHE CANT BE HERE.I DONT KNOW WHAT I SHOULD DO WITH HER.IF I TAKE HER TO THE HUMANE SOCIETY SHE WONT GET ADOPTED SHE IS OLD AND MEAN,IF I MAKE HER AN OUTSIDE CAT SHE GETS HIT OR EATING.OR THERE THE OTHER OPTION OF HAVING HER PUT DOWN I DONT KNOW WHAT TO DO .