This was an extremely important point that you forgot:
“i forgot to add that his sister asked me if she and him can get a ride because she didnt want him going with not jewish girls and she rather him go with a jewish girl.”
This is a delicate balancing act. Some girls can just refuse to talk to any and all men which makes life easier. You should talk to a Rabbi about this situation.
Having his sister in the car will mean the two of you have a chaperone, so it is mutar al pi Din. Just make it clear -both to him and to yourself- that without a chaperone, you aren’t going to give him a ride. Without a chaperone, it is better for him to go with the non-Jewish woman.
What the other adults are telling you about this boy sucking you into his world is correct, but if there is a way to help that is mutar al pi din, then you can rely on the Halacha to protect you.
If you don’t, then the boy will use this as evidence of his pariah status. I’m telling you to help when the Halacha allows you to, so he won’t get any angrier than he (probably) already is.
That’s about all you can do to help him. Befriending him is not going to help. In fact it will probably make things worse. Do what you can within the restrictions of Halacha, and hopefully next semester he won’t be in any of your classes.
Of course, there is one more thing you can do. You can daven for him. Get his name from his sister and say tehillim and daven for the zechus of the amiras tehillim to go to him.