The fact that you fear not being enough, not being able to get what you want, not feeling able to get where you want, that you feel so insecure about yourself is probably not just related with your childhood but also with past friendships or any other type of relationship that didn't end well or in which you weren't treated correctly. You were probably left out from group activities and jokes or not invited to places; you were made to believe you were very important but at the same time you were kept hidden and later you were left alone and forgotten as something of not great value; you were probably easily judged as uninterested because of your decisions or behaviours without asking for further reasons...
I know all these experiences (and many more than these ofc) hit you deep and now are rooted inside of you as a confirmation of your unworthiness and unlovability but it was not your fault. Or at least not just because of your decisions or behaviour (of which not everyone has the empathy to understand or even guess/imagine the reasons, if you don't talk about it): in relationships there are always at least two people involved. And when one of them moves away or leaves you out of their life without asking for or giving an explanation, it's a relationship that is already crumbling (and it's best if it ended this way, even if it pains you because you felt guilty about it). When there's not communication nor interest in the other and in their feelings, despite how strong and indipendent they may look, despite how far they may have moved, a relationship is already ended.
It's not about your worth or lovability, which you possess just because you're alive. It's just about people's decisions, it's about lives taking different turns, it's about the fact that some relationships just need to end or evolve into something different that is not a deep friendship anymore (if you both agree ofc). It's about people growing and changing, and following their own path.
Keep going on onto yours so to find new friends and even lovers if you want (cause you will anyway: life is made of cycles, as you had friends in the past, you'll have friends in the future; as you didn't have good friends in the past you will have good friends in the future. It's all about you, you can change your life at any given minute. Take your time to understand your emotions and process them but then let the past go, heal and move on to something new -and even better, seen how you were treated).