Hi Amethystt,
if you really cherish that friendship with your that good friend that has broke with you, how about trying to connect with her again and apologise to her? Well you may not be in the wrong but sometimes we hurt our friends without knowing it. If I were you, I will try hard to reach out to her to apologise. In the end, she may or may not accept your apology by at least you tried and you know your mind will be at peace knowing that you have tried.

To be honest, I am also in a similiar situation as you, i.e. i have many friends, some close some not so close but i also find it difficult to connect with them, including those that I am closed to. Very often, I find myself nothing to talk about even when I am in an outing with my closed friends. It is weird but this feeling has been with me for many years already and I did not try to find a way to fix it. Hence, I can comprehend the loneliness in you as I do feel very lonely too. Perhaps the way to kill our loneliness is to find some hobbies or interest to kill our time. You may want to find things to do that interest you. As for friends, I have come to realisation that not all friends click with us. If we want to connect with our friends, probably we also need to put in some effort to try to connect with them. It takes two hands to clap. I wish you all the best in seeking out true friends that could connect with you.

Have a lovely day,
Emma