Jealous of my best friend’s other friends

Every time she posts a photo with someone else, I feel a little sick inside—like I’m about to be replaced and forgotten.

I know it sounds silly, but I need to know if anyone else has ever felt this way. My best friend and I are super close, and I really value our friendship. We’ve been there for each other through so much, and I honestly don’t think I’ve ever been closer to anyone outside of family.

But I get this wave of jealousy whenever she hangs out with someone else, especially if she posts about it on social media. Not because I don’t want her to have other friends, but because I’m scared she’ll have more fun with them. That they’ll get closer. That one day I won’t be her person anymore.

I’ve never said anything to her, obviously. I don’t want to come across as controlling or insecure, and I really do want her to enjoy time with other people. I just hate this feeling like I’m not enough, or like I’m slowly being replaced and I won’t even realize until it’s too late.

Has anyone else gone through this with a close friend? How do you deal with the jealousy without letting it ruin things?