I can really relate to everything you wrote and described, especially being indecisive and fearing embarrassment in social settings and just your overall feeling of depression. You express yourself very well and sound highly intelligent. If you have a family member or your physician that you can reach out to, do it. Don't hold back out of fear. And if they don't hear your concerns in the way you need them to, find someone else who can help guide you in the right direction.
I think it's amazing that you've accomplished a black belt in karate. 10 years shows your ability to commit and be devoted and focused. Don't give up on yourself. It is painful but you will find your way. Keep trying to be optimistic.