I'm tired of pretending that I'm fine TW - self harm

I feel like I'm just existing, like nothings worth doing or wasting energy for and basically just feel hopeless. I started to self-harm again even tho I was 2 months clean. But no one knows that. everyone only knows the happy, cheerful me that I've been faking for years and I just can't anymore. I barely have the energy to talk and I just can't pretend I'm fine anymore. I've been distancing myself from everyone and barely kept in touch during lockdown cause I don't want them to see how bad I'm feeling. But now that school starts again I see all the people in person again I need to appear fine. I can feel how I'm losing my friends because I don't respond to messages immediately and because I'm not so cheerful at school anymore. A friend I know since childhood gets mad at me every time I don't sound like I'm happy to talk to her on the phone. And I want to tell her that I'm trying, that I'm happy to hear from her but I feel like shit and just don't have the energy. And I miss my friends so much, I need them but I don't have the energy to reach out to them and I don't think that they would want to hear about my depression anyway. On top of that, I'm very bad at communication and really don't know how to express my emotions or explain what I'm feeling ( see the awkward paragraph at the top where I fail to explain how I feel). I'm just tired of everyone expecting me to be happy all the time, but I feel like I should be happy. I mean nothing really bad has happened to me and I still feel terrible.