Girlfriend doesn't treat me right?

I'll try and get straight to the point, last night I told my girlfriend I have a fear of flying. I'm supposed to fly to see her soon. Anyway, she basically tells me to man up and that I'm scared of everything (which isn't true at all). We end up getting in a fight, she calls me asshole, idiot, moron...tells me I'm such an awful boyfriend. In the past, she has made threats before like "I'm going to tell your family how much of an asshole you are"...or "I'm going to tell your family your darkest secrets"...so I end up folding and always going back to her. She goes crazy...it's like she becomes a completely different person. Well last night, I tell her my feelings for her have changed. She goes ballistic. Tells me I've wasted her time...tells me I've strung her along and that she's so young and naive (making me sound like a real creep). The only reason I've changed my mind is because she becomes verbally abusive and tries to use emotional black mail on me! Afterwards she feels bad and wants us to get back together. Honestly I wish she was just out of my life. Any advice?