Trying to talk made me feel worse - and my depression nosedived because of it

I'm relatively new here, and have been reluctant to post until now.

Since I started university in september, everything has just plummeted. I self-harm more frequently, and the longer a resist it, the deeper I cut when i inevitably crack. I tried talking to teachers a few years back (this is a looonnnggg running problem now), but choked and couldn't do it. I tried explaining just the very basics to my parents, after they saw my scarred arm. I have never in my life felt more empty, guilty, vulnerable, or frustrated as I was then. from that point on, everything was just downhill with the very worst bouts coming directly after good news, like my neice being born. My flat mates know about me self-harming, and tried to be as supportive as they could at first. I try to avoid them if I need to cut myself, as blood isn't exactly the prettiest sight. Recently I've started 'running through' what actually ending it would be like. How would I do it? what would my family think? I've managed to resist those thoughts until now, but everything is just 'meh' to me now. I don't care about anything. I wont eat or sleep for days at a time, and when I do it's literally quick foods like microwave meals, or when I sleep I get 4 hours tops. I found it easier writing this forum post, as speaking in person is incredibly intimidating, and often unhelpful. Not going in to detail about it is my last defence. Atleast if I don't talk about it I can pretend it isn't real, right? While im writing this post I'm supposed to be doing university work, but I can't do it. I can't control my thoughts anymore, and music doesn't help now either. What exactly can I do?? I see no light at the end of the tunnel.