I feel like a failure

I suffer from very bad depression but it’s confusing some days it’s like I don’t even have it and others I wonder what it is that keeps me alive. I feel like no one cares about me but at the same time I’m afraid that if I die still no one will care.but what can I explicit when I don’t even like myself. And just like that my mind spirals into these thoughts and I just got too deep yesterday and after almost being three weeks clean I cut again. And I feel even worse because my SO was trying to talk me out of it and I let him think I wasn’t and he was so happy afterward and proud thinking I didn’t but I did. A lot. I feel like such a fucking joke and a horrible person it just makes me want to cut again and I don’t know what to do anymore with this endless cycle that only ends when I cut too deep....