You are an articulate and intelligent man as shown through your writing skills. I imagine this translates to the same when you socialise. Perhaps you don't realise this. This is a great deal going for you.

You are definitely not alone; in fact, what you describe I think many people experience. I am good enough? Will I be accepted? Gee, my life is run by such thoughts.But I plod my way forward wearing a mask of confidence. Perhaps this isn't the best thing to do as it just covers up what I am truly feeling but it does get me through the day and awkward situations.

CBT (Cognitive Behaviour Therapy) has helped with this. It may be helpful for you. The problem - my problem - is that you need to keep up with it everyday. I do it for a while, my life improves, I slack off, then realise things are difficult again. I start it up, do it for a while, and etc. So while CBT is a great thing, it is only as good a solution as the commitment you make towards it.

CBT teaches us there are a number of thinking styles that get in the way. Once we recognise those that affect and trouble us the most then we can apply learned skills to combating the thinking. We can't erase the negative thoughts but we can cope by stressing to ourselves alternate more positive thoughts.

For example, I think you and I both have a tendancy to 'negate the positive'. We put aside all the positive things we are/do and concentrate or obsess on what we interpret as not being good. The solution is to consider in what way such thinking is actually an advantage to us. What then actually is and how can we recognise this, etc.