Seek professional help. You've identified a symptom, now the best thing you can do is get the right person to help you explore the cause and fix it. Whether that is a personal coach, or a licenced psychiatrist, I leave at your discretion. Just do it, it's a google search away from you.
'Over thinking' and 'self destruction' sound like symptoms of depression/anxiety. If that is the case, you will eventually have to seek out a professional for diagnosis and treatment. Importantly, you can't rule out mental health issues without consulting a professional, especially when these problematic patterns of behaviour are present in so many areas of your life. If you do have a mental health issue then it's likely that you won't be able to fix the issues you're experiencing without first treating it, which is why consulting a professional is such an important step.
Independently of the existence of possible mental health issues, a psychologist will be able to equip you with tools (cbt etc.) to facilitate the changes that you want to make, and support you through them.
As a mid 20's white-male who has experienced a somewhat similar situation, I wish that I had sought out professional help sooner. If I had, repairing the damage caused by un-diagnosed major depressive disorder and social anxiety would have been a much easier task.