It sounds like you are stretched really thin and burnt out. School stresses are definitely hard to deal with. It's mentally taxing especially when the money it costs to be there is on the line. I've been there, and I totally get how you're feeling.
I know you've got a lot on your plate right now. But if I can say one thing: not finishing an assignment or two will not cost you your education. Especially when the stressload could cost you your life. You are putting tons of pressure on yourself to be perfect and please everyone else but you're rotting inside. It might be time to put yourself and your mental health as priority #1.
You have the ability to put your studies on hold and come back to it if you're finding it to be too much right now. I know lots of people that have had to do this and there is absolutely no shame in that. If you don't want to do that or that option isn't available to you, let a few assignments go past due to take some time for yourself. Have you spoken to anyone about how you're feeling? Would your girlfriend be a trusted confident?
Please try and remember that you aren't perfect; you are human. And to be human is to make mistakes. And to be human is to have feelings, good and bad. If your bad is greatly outweighing your good, then you need to look after yourself. Please take some time for you. You deserve it