Everyone Treats Me Like Garbage !

I feel so disappointed right now. I feel like noone near me can really understand me or treat me right. My friends don't pay attention to me and they rarely invite me out with them anymore. I also think that they are gossiping me behind my back because they weren't like this before. I catch them talking to each other in very low voices and then staring at me and when I asked them to tell me what's wrong they told me it's nothing.

Also my professor insulted me in front of everyone three days ago. He was writing something on the board but I just couldn't concentrate, so I kept biting my nails and thought other things. Then suddenly he asked me a question I didn't know the answer to. He then called me "slow" and he told me "I didn't expect anything more". Everyone was staring at me for the rest of the period. I just wanted to die at that moment. I don't know why but it hurt more than I thought it would. I'm a good student and I never did anything to justify those words.

I hope this is just a phase but I don't think anything will change anytime soon. I never felt so insecure and unsure of myself.