Feeling insecure

Today, Bryan announce to us that he is leaving us for a better future. I am happy for him, but somehow, heart feel sourish. I am worry at that point of time because i put all my hope on him and having him leaving the company make me feel alone and expose to danger, like i would not have anyone backing me again. I feel shaky. I cried that night to sleep.. That is because i know i am losing a good boss and i no longer can see my career path..