I have a similar situation just reversed. My bully I have to put in a cage at night. The rest of the flock all do fine. They are all younger than she is and smaller. I'm hoping she will calm her self down. She is 26 weeks and should be laying but hasn't yet. So I'm just waiting for and egg to she if she will be better after that. I feel badly putting her by herself in a cage at night but at least she can free range during the day. Wish I had some advise. I am learning with chickens it is just trail and error. Sometimes things work out sometimes things don't. I have had to give up 3 chickens to get my flock to where it is now. I am really hoping I can make this chicken work herself into this new flock I have added. Good luck.