I see you and I feel for you.
One good friend outweighs a dozen bad friends. People come and go, and that's okay. They weren't meant to be in your life. Everyone has people filters, the best people for you will stay, and those who, in the long term, aren't going to be supportive or beneficial will be filtered out. No one is alone in this world, for some it just takes longer to be placed in with the people they need.
Thoughts can be horrible, but it's important to address your schemas, because it's not natural or healthy to think in the destructive way a lot of us do. Granted, it's not easy, but small steps every day are what'll reform you in the coming months. We grow, we learn, we strive to be the best version of ourselves we can be. Your situation, in your eyes, may not be ideal, but maybe some time being more isolated will call for you to take a step back and evaluate all that's around you. The people, the environment, the prospects. And then, you can work on that.
You cannot self sabotage anymore, you're done with that! You have to do everything for your best interests. You feel your emotions, you hear your thoughts. Address them.
As for university, I know. The pressure of going, and the pressure of everyone around you wanting to know what your outcome is can be tiring. But, if you have any doubt, draw up your options immediately. Can you transfer to a different course? Is this course going to offer something for you in the future? Do you even enjoy this course and its prospects? Does it provide optimism for what your future can be like?
If the answer to some of those questions is no, maybe consider a year out. You do not, of all things, want to put yourself in tens of thousands of pounds in debt because you felt you had to go to university. Work, build some skills on online courses, make yourself an appealing prospective student/employee. You have to make your life valuable, make your time worth money, and make yourself happy.
No more doom spiralling. No more pessimism.
Map out your life path with your current plan, and simply think. It's up to you.
It's your life. Decide.
Always here