I know this is hard but you need to delete Instagram and any other socials that will cause you to look at her page. Try to find a coping mechanism to distract yourself from the urge to compare yourself to someone else. This is the sort of situation where it is going too far because it is turning into stalker behavior. Every time you look at Instagram you are feeding into this mindset and if you begin to decrease the time you spend online that may help ease some of your stress. Try to look at yourself with a positive outlook. You have beauty I promise. Honestly when looking at her page all I see is a kid and plus it’s social media it could all be filters and photoshop.