Your T reacting with sarcasm sounds horrible, and very untherapeutic. If he does stuff like that no wonder you are feeling lousy. I think that therapy has the potential to help with self worth. I remember once telling my t about an incident that occurred when I was left alone at the age of 3. My T picked out how well I'd handled it and looked after myself, which made me feel good, I had never looked at the incident like that. I think that there are a lot of subtle things that a T can do that can help.