The_fat_baby

Well yeah but I want justice

My crazy ex logged into me and my friends minecraft server without permission and lived without ruining anything. Then we decided to ban her because she wouldn't stop getting on without consent and was starting to change my room around. After we banned her. We got on about a month later and she had destroyed my room. Killed my animals and griefed a lot of our kingdom that took us months to make. How did she get on? And how can I actually stop her from getting on and ruining everything