I am psychosomatic & have tightness of chest. how can i sing?

Try 2 things at once: First, one would try to solve psychiatric issues with her primary care doctor and her psychiatrist... which means talk therapy and sometimes also medications. At the same time, she might try different music lessons, eventually leading to singing lessons. If things don't work out, she can do something else she was destined to do in life (meaning don't try to force things).