QuoteSome people that I've been talking with have told me that I don't exsist.
That is vague and I think further context is needed to accurately understand the situation. Some believe that nothing exists. Are they saying, nothing exists, therefore the 'you' that you believe to be you doesn't exist, because noone exists within the framework of what we believe to be reality?
If that is the case, you got into a philosophical debate and that is their viewpoint (which you can counter rather successfully with, "If you don't exist, then why should I listen to your viewpoint, you're just a figment of my perceived reality?" Or, restated, "What makes your perceived reality better than my perceived reality?" In truth, they can only come back with something from their own perspective, which is only valid for their reality and as such, has no truth for your own.
If they are telling you that you are mistaken in the way you feel, and you don't exist as you feel, then simply ask them how it is that they know how you feel? Secondly, ask them what better qualifier exists as to who you are other than how you feel on a consistent day-to-day basis?
I think more information on the situation is needed before I jump to a conclusion personally.
*edited for clarity*