You may talk here any time. Someone will read and respond. I kind of obsess over PC.
You're certainly in depression. I know that "too heavy" feeling and "do nothing because anything is too much."
Unfortunately I don't have a cure. I do know that doing something might help. Find anything positive to do, even something you enjoy as long as it's a positive, and do a little of it. It could help. Missing class is possibly going to hurt you in the long term. I assume classes because you used the word "lectures." Try to get back into them soon, please. This is your future and I know you care about it, but you're having trouble right now. The only person that truly cares about you first is you. Even if you're in a relationship with the best SO ever, you'll still have to take care of you first. I totally get the lonely part though. I've never had a relationship I didn't still feel somewhat alone in. I need a cat.