You said that you already have a job, can't you support yourself? If your family stresses you then, move out of the house. You're too engrossed with your insecurities that you thought you have no true friend. Maybe you just have to reach out to other people outside your family so you can form friendship. Having friends can help you out of thinking suicide and can make you be a better person than you thought you are. Maybe when you achieved something for yourself your family's opinion of you will change.
Rather than thinking about suicide, plan on how to get your own place. That would be a big step for independence that will remove you of your stressors. By doing so, you are taking control of yourself and your fate.
Hope this helps.
Hi there, I'm sorry you're feeling this way.
Have you reached out to a professional for help? That really needs to happen. It sounds like you would benefit from some intensive therapy, to work on your self esteem, sense of self worth, and your view of yourself in general.
As for the situation with the car, it sounds odd. What kinds of circumstances does your sister threaten to take the car? Can you give an example? It COULD be that she perhaps has some legitimate concerns/issues, and it could be a bit of a control thing...or even a little bit of both. Did you ask for a car? Do you work? Do you pay for any of the car expenses (ie insurance?). Regardless of what's going on with that, your sister shouldn't be calling you names.
Really, the best thing you could do, besides making getting some help a priority, is working towards being independent of your family. Are you in college? If you would get your own place, and your own car, that would eliminate a lot of those stressors for you.
Keep in touch, let us know how you're doing. It goes without saying that if you feel you're at risk for hurting yourself, you need to seek help immediately. Suicide is never the answer.