Your negative thoughts are obviously distressing. The most effective and efficient way to conquer negative thinking is to focus on reality. For instance, in the case of you believing that “no one likes you” ask yourself this question: “what evidence do I have to support this belief?” In all likelihood, there will be no evidence to support any of your negative beliefs.
What complicates matters is your expressed difficulty in “grasping reality.” I’m not precisely certain what you meant by that expression. Generally speaking, if you have difficulty determining what is real and what is not, then I would strongly suggest seeing a mental health professional. A mental health professional could help you to stay grounded in reality. A therapist could also assist you with your negative thinking. Again, the focus would be on keeping your thoughts based in reality.
It is always advantageous to seek professional help when you’re struggling with psychological problems. You may ultimately be able to solve these problems on your own but it would be much more efficient if you met with a professional who has been specifically trained to deal with psychological problems. There’s no reason to prolong your suffering when help is available. Please take care.