I never had a large amount of gender dysphoria.  A few weeks ago, if someone had even mentioned the idea that I could trans, I probably would have laughed.  However, a couple of days ago it was as if all the pieces of a puzzle snapped into place.  It's crazy how I managed to ignore something so obvious.
The problem is that now I'm feeling sick, really sick.  It feels like I'm suffocating.  I have to constantly stop what I'm doing and force myself to breathe.  I can hardly sleep, and my appetite is greatly diminishing.  Is it normally for these feelings to be so sudden?  It feels like they came out of nowhere!
I know I need to talk to someone.  I feel like I'll go insane if I don't.  In a moment of clear-headedness I called my mom, who is on vacation out of state, and told her I had something extremely important to tell her when she returned from her trip in two days.  She doesn't know what I have to tell her, but she promised she would support me no matter what.
The problem is that I'm chickening out.  I constantly have moments where I disengage from reality.  I keep telling myself that there's no way this can be real.  I'm just hallucinating, dreaming, or reading a story.  That there is no way I could really be feeling like this.  
I'm panicking to the extreme and I'm scared.  This is just too big of an event.  What do I do?