TIFU by 'apologizing' to someone

So, I'm young, still in highschool and I fell out with someone I had been friends with for about six years. Lets call her Libby. She was my best friend, but since a few weeks ago I had felt really left out because she'd started to get closer to one of our other friends till the point they were making arrangements in front of me. I wasn't angry for the fact they were making plans Infront of me but I decided at lunch I would go out without texting them to give them space to make their plans. That's where I messed up. I didn't text. Near the end of lunch they came up to me and they asked me why I never texted them and I said that I didn't know. They both then stormed off.

I thought this was okay, it would've gave me a break from them for a while since this wasn't the first time we'd argued for something like this. But I was very wrong. The next day I had a friend text me saying that Libby had been calling me a bitch behind my back and I wasn't having that, I texted her asking her to meet up with me and calling her a twat and stuff like that. We argued all throughout lunch until the bell went, when I got home I got a text from a random number saying really, really bad things about me. So i texted Libby saying that this had gone to far. She replied with "I don't know who that is" then blocked me. The thing is, she had to know who that person was since it had very personal information about me and things we had argued about previously. I told my gran about it and she said she was going to get the police involved, I said no because this type of thing happens all of the time but I text one of my other friends saying to tell Libby to unblock me and that my gran was getting the police involved. A while after Libby unblocked me and told me she was sorry and that she didn't know that it was actually her best friend from her home country that had texted me it and I said, "it was her??" I told her sorry wasn't enough though, by that I meant she needed to come apologize to me in real life instead of over text. We argued until she blocked me. We hadn't spoke for a couple of weeks after that.

Today was her birthday, I never noticed until a group chat notification popped up where it was one of my other friends birthdays who had the same birthday as Libby. I then texted Libby saying happy birthday and that I had been thinking about what happened and I wanted us both to say sorry to eachother. I then remembered I was still blocked so I asked one of her friends to ask if she could unblock me, she asked me why and I told her it's because I wanted for us to not argue anymore. She said okay and I said thanks. Libby then texted me saying "what" and I resent her the messages it took a while but she read them then instead of typing, sent me a voice note saying what she felt, I heard friends laughing in the background and she'd occasionally laugh with them. I kept telling her how I felt aswell, over text instead of voice note, keep that in mind, she kept saying she just didn't care about me anymore which made me pretty upset as I was so attached to Libby and at this point I felt like I was in the wrong but was still trying to defend myself. I couldn't just say I was sorry because that would make me look weaker than I already am and it probably wouldn't make her come back to me or anything. (I should probably mention that every argument we have ever had, ended in me coming back to her.) Her saying she didn't care anymore made me really angry so I ended our argument with saying how she was a pedophile and so was our other friends. (I should mention she is also young but has child p0r^ on her phone which is pretty awful and our other friend always laughed at it.)

The friend that I had texted previously to ask her to tell noemi to unblock me, texted me saying horrible things, we then argued because she said I lied to her saying I would apologise to Libby but didn't. I honestly tried but it didn't work out and I tried to tell her this but she wasn't having it. (Libby had showed her screenshots of our conversation, I'm guessing that's why she did voice notes, because nobody could hear them through a screenshot, but you could see texts through a screenshot.)

I really feel like my life is over, I have nobody left apart from family and I'm genuinely scared to go to school tomorrow incase they come up to me. If I just didn't text Libby trying to make up, this would've never happened.

What can I do to fix this, or better, avoid it?

TL;DR: by trying to apologise to someone but messing it up by getting angry