I Miss Someone Very Much

We were not exactly in a romantic relationship before we stopped being close. However, we were close and relatable. Best friends, if I may. He was new to the school and we are both Cantonese in this international school. Long story short, we were close, then he was just distant and hung out with other people. I feel extremely hurt and a friend suggested to me that I shouldn't chase him and let him do the chasing. It has already been a week and we still haven't texted each other. I really want to text him but I'm not sure if I should.
I really want him back and I am struggling with whether I should text him or not. Either I chase him and risk him thinking I am clingy, or that I don't chase him and risk losing him forever.