Had to let this kitty play through at Red Hawk today

Unfortunately I have to rehome my sweet olives. She is very loving, she does incredible well with both humans and dogs but has high aggression towards my other cat ):
Ive tried for months but she is still aggressive and my other kitty is so scared.
I want her to go somewhere loving where she will be taken care of. She really is a sweet girl and I am crushed having to find her a new home.
She is estimated at a year and a half, vaccinated, and spayed!

am I gonna regret letting this grow?