I impregnated my best friends 14 year old sister
Why would you impregnate a 14 year old child?
I'm too young to have kids, I rather die
If the sister was really 14 years old then this is considered statutory rape. You shouldn't be having sex with underage girls.
She said she was 16 and was ok with this.
Wrong. You should have known better, like ask your friend how old she was. You need to turn your self in because her parents will find out and so will everyone else.