Everyone thinks I'm smart but I feel like a fraud?

I graduated with highest grade of my year. It was a bad school. But I always thought it still meant something, I still had to work for them. My major was also social studies. I mainly studied topics like religion, history, sociologi, philosophy. 

After graduation I decided to study science and math (chemistry, physics, biology and math) I knew it was going to be challenging but I truly thought I could do it.3 months in to the programme I was exhausted, It felt like I constantly had to walk through an uphill battle while rocks were being thrown at me. I was studying for hours everyday, while always feeling behind. I would prepare days before we were supposed to do science experiments and I would still embarass myself by my lack of knowledge. I am not exaggerating, I could feel that the person that would be my partner for the day would start to sigh and be disappointed that they got me.I suddenly dropped out, I just couldn't take it, I just feel so stupid. Like genuinely dumb. I feel pathetic that I even thought I could do this. My plan was to go into STEM-field but I feel like I don't deserve to aim that high. Like who do I think I am that I actually think I can do this.I am embarrassed to tell the people around me. I know I disapointed everyone by dropping out. Everyone sees me as this straight A student who's super smart and I feel like a fraud. People constantly describe me as the smart person when I'm not.Idk what I want from posting this, maybe just some advice..