I can only speak from my own experiences but I have been in a similar position.
To be happier with your life, you need to make changes. You need to leave your toxic social circle, you need to find people you value who value you. If you're unfulfilled and you can't discuss your interests with anyone, you need to start taking action to be fulfilled and make connections that align with you.
Your current paranoia, sense of being trapped and lack of motivation are probably all symptoms of your situation and your extremely low mental state.
What benefited me in a similar situation (after some years of feeling like this and getting to be a point where I was almost constantly thinking of killing myself) was going to my doctor, going through a cycle of 3-4 antidepressants until I found one I could bear, and seeing a therapist. I found the antidepressants stabilized my mood enough that I could gradually begin to make changes in my life, and I could track my progress in making those changes with my therapist to be assured I was moving in a positive direction and thinking about what I was doing. I saw my therapist for ~6 months and was on antidepressants for ~1 1/2 years. I took about 3 months off work sick over this time, unfortunately I was working for an employer with decent sick terms and maybe you're not so fortunate there.
My life isn't perfect now and I still feel I have to do a lot of work to get to a place where I will be truly happy, but I have been able to come off the antidepressants and experience my emotions more and I'm still in a much better place. When you are as extremely compromised as it sounds like you are, it's very difficult to improve your situation. So much of your resources are spent just trying to get through each day. Medication helped smooth out my lows so I could get in a position to get better.