Silbling rivalry at its best! lol

Unless you've given her a reason to make false conclusions, there's probably nothing you can say to change her way of thinking.
Step out of the relationship for a moment and re-evaluate the entire situation.
If she's that insecure with the relationship, there's no way you two will be able to ever achieve a healthy, loving relationship.

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I am Angie between the eyes! :::head tilt:::™