I am deeply disappointed due to my social anxiety

I attended an event with my family today and seeing the severity of my social anxiety, I just broke down today. It was really disappointing when I couldn't vibe with anyone when guests arrived while even cousins younger than me were vibing together. I could only pretend getting along with others while pretending to smile, while my uncle mocked me loudly in front of everyone for my inability to smile properly and I felt even worse. I felt as if my real self is gone today. I couldn't even talk properly with people and felt like a broken toy today. Felt as if every thing I am doing is fake and I don't know a thing. I am already deeply heartbroken due to a romantic rejection from the past and the social anxiety makes me feel even more sure that I will never make a girlfriend. Not with a broken potential to vibe with people