How do I tell my friends I'm swtiching schools?

I decided to switch schools a few weeks ago and I didn't tell my friends because my mom wanted to wait until I was registered. I didn't want to wait so long because I knew they would be upset because we had talked about having high school memories together and stuff. I'm getting registered tomorrow and I planned on telling them all tomorrow, but one of my friends called me today and said that she was going to a different school too. I felt a little relieved that I wouldn't be the only one leaving, so I told her that I was leaving too, but five minutes after we hung up another friend of mine called me and said that she heard I wasn't coming back. I was in complete shock that she knew already and I could barely speak. She sounded really upset and she quickly hung up. I texted her back to tell her not to tell anyone so they could hear it from me and she started asking me why because she thought we would spend high school together! She just seemed really upset because I didn't tell her sooner. So, my question is how should I tell all my friends that I won't be coming back to school? I was going to text them, because there are about ten people I was going to tell, but it seems too impersonal. Should I call every person? I don't even know if I'd have time. I just don't know what to do anymore. And I don't want them to be angry at me for telling them I was going, because I didn't even know until a few weeks ago!