OMG I JUST

I just broke my E-srting yesterday while tuning it down cause it was sharp....that was wierd, i understand going up but down?
 
This is the first string i broke in 3 years....It was one of the Fender Classic ''Bullet'' strings....but what the hell....do I buy all new strings now or what?
And how I broke it? Well, My guitar only has 21 frets and I just HAD to play that High 24th fret bend, did it a couple times before....lol Never again?