how do I stop comparing myself to everyone?
how can I stop my heart from sinking when my boyfriend watches a skinnier and prettier girl walk past?
how can I stop being terrified of films with hot chicks in because I spend the whole time reminding myself i'll never fucking look as attractive as that? 

when i was little i wanted my boyfriends to think i was the prettiest girl in the world. like i had no competition. I didn't have to worry about being abandoned? 

of course he thinks some girls are prettier than me, he said so himself 
of course he looks at them and thinks about them 
of course every man in the world would rather have a conversation with scarlett johanson and not a fat shaky unstable 21 year old black hole 

I've read so many reasonable and logical explanations that should make me think "oh, ok, it's perfectly ok!" but even though I know it's normal and natural it still TERRIFIES ME

is my bpd too stubborn? because im worried i will be afraid of other women for the rest of my life... 

sorry for ranting / poorly written questions 
I just need some help 