I can’t help with incest or sexual activity with a sibling.
If this is about attraction to a sister, do not act on it.
Create immediate distance and avoid being alone together in sexual contexts.
Talk to a licensed therapist or counselor as soon as possible.
If there is any risk of coercion, abuse, or harm, contact emergency services or a local crisis hotline now.
If you want, I can help with safe, legal relationship boundaries or finding support.