I have the exact same feeling with you, which is dealing with moving on. I actually also have a very similar reason as to why I lost my best friend.

I met this person more than half a year ago. They were a friend of a friend that was introduced to a friend group I was in. Fast forward a few months, the current friend group I had, where there were people I had been close friends with for over 10 years with, shit talked me and some other friends in the group. They were incredibly toxic so I decided to leave a 10+ year friendship with several people I know.

A few other people left with me, including the person I became best friends with. Our friendship, after leaving the group was very great. Both of us really enjoyed each other’s companies and really thought we’d be good lifelong friends. Eventually, I had the same mistakes that you committed. I became too clingy, I would depend my happiness to them, and I associated a part of my future with them. I noticed that slowly, they became less interactive with me, so we decided to talk. They told that what I did was wrong and toxic and I owned up to my mistakes. There was this other friend I had that was jealous that I am closer to my best friend that they were, so that hurt me when I came to know that. I slowly began distancing myself and all I kept thinking about was my problem with my best friend. Apparently, they did not like talking about past events and told me that I kept bringing it up although it was obvious it was not yet fixed. It was obvious that we weren’t as close as before and all I wanted to do was ask them about it.

Eventually I just decided to not interact with them as much compared to last time, because I know they do not really like with the way they interact with me.