<human>: Condense the text into a few key points

So I was dating a girl, also 16, for about a year and a half, and over the past few months I suddenly became what many would call an asshole. The detail of the things I did isn't overly important, but I didn't realise I was doing them until it was too late. She broke up with me a few weeks ago, but she essentially told her friend exactly why, who then went on to relay that to myself. After reflecting for the past few weeks, I believe I've narrowed down everything I could have done better and many of the things about myself that developed and in turn destroyed the relationship and I think I've dealt with them accordingly, although I've had absolutely no way to prove that to her. So now I want a second chance, which sounds like a big ask and I get that but at the same time I feel it'd go well. But I have one teensy obstacle. Unsurprisingly, I'm not exactly her favourite person in the world. I was originally blocked through every form of communication possible, but I have since been unblocked, however she still doesn't want to even speak to me about anything, let alone this. Not only that, but she is incredibly stubborn, and once she makes her mind up on something it's incredibly hard to convince her otherwise. I haven't asked for a second shot yet because I don't feel that's the greatest thing to do when she won't even talk to me, but I don't know what I can do. I'm completely stuck on what to do next. There aren't many people she listens to, but I'm friends with one of those that she does and he said that he would be happy to help me in any way he can. But I don't know what to do next, I feel that whatever direction I go in its not going to do anything. I've done the obvious like apologise, and I don't think she exactly hates me any more, but she certainly doesn't like me either. I'm out of ideas, Ive tried everything I can think of and her position has stayed almost the same. Help!
<bot>: girlfriend dumped me, I fixed my problems, but I don't know what I can do to get a second chance.