It would have been better if she had had the guts to tell you why she was ending the friendship but sadly people prefer to avoid the difficult conversation and just slowly back away, hoping the other person will get the message.
It's often advised on here. And claimed to be an attempt to avoid hurting the other person which makes me laugh because that's bollocks.
That said, she has through her actions made it very clear she no longer wants you in her life. You must respect that. It's unfair that you don't know why (if you dont) but life has never promised us fairness. Or closure for thst matter.
I think you do know what the problem is. You just don't want to admit it, maybe even to yourself. Perhaps your friend did talk to you about your neediness or lack of boundaries in the past but you didn't understand what she was saying.
You come across as very intense, quite dramatic and some of your replies have been somewhat manipulative and passive aggressive. I'm not saying this is intentional but it is how you come across. I presume this is how you are in real life and if so, people will continue to pull away from you.
Which is sad because it will make you more intense, fearful, dramatic etc.
You need some sort of therapy and to build your confidence. See if you can talk to your GP and find out what is available.
You can use this painful experience to turn your life around.