You are so young!

Ashlee RossEx-husband and you Pete WentzNow, they are parents to a teenager. Their son is now grown up. Bronx, celebrated his 13th birthday over the weekend—and the “Pieces of Me” singer couldn’t help but gush over her son’s milestone.

This is 13. Happy Birthday Bronx! Ashlee shared the message in an Instagram post on November 21. You are the most cool teenager. You are my best friend. “I LOVE YOU.” The post included a black-and-white photo of Ashlee with her teenage son, which made for a sweet moment mother-son.

Ashlee was not the only person to celebrate the birthday boy. Famous friends shared their joy and blessings in the comments. “OMG 13,” Rachel Zoe wrote. Makeup artist Mary Phillips added, “Stop!!! It feels like yesterday that he was in my belly.” 

Bronx’s stepdad, Evan RossThe party was attended also by others.