Wow, that's low. Are Ты sure they're really best friend quality? They could be doing it for many reasons... Maybe they feel insecure. Maybe they have a crush on him. Maybe they want to look cool. или they could just not know what the problem with that is.
Your friend is a backstabber. Why would a friend Показать embarrassing Видео of Ты to your old boyfriend? She is betraying Ты and Ты should not be Друзья with this girl. Ты can get better Друзья than her.