Anyone else panic when a relationship ended but actually realized it was for the better?

I (19F) have worked with this guy (24M) for about three years. I met him in high school because he was the leader of our theatre tech club. He later became my boss after he offered me an internship my senior year that has continued now that I am in college (I return whenever he asked for help since my college is not far away).

I thought I would continue this job throughout college and there was also talks of hiring me full time after college but he recently told me that he was planning on quitting in a few weeks. Initially I panicked because I thought my entire future was going to change in a bad way. Him quitting also means that my internship will end, and the joy that I find at the job will also be gone. At the same time I am upset that he is quitting I realized how much of my life this job has taken up- I have sacrificed friendships in high school and college because I have been there every time he asked without hesitation. A part of me is excited because I will now not be held back in college due to my constant tie to high school. I can put my full effort into being involved in college life without feeling like I am missing out in my job.

He has now said that he is going to wait to quit until January so at this point he might not quit at all. I have mixed feelings now because the initial news of his leaving made me realize the upside to the situation.

TL;DR
I realized how much I have sacrificed because of a relationship with a person but not until the relationship ended even though I thought it wouldn’t end.