Did I betray and break my promise to her (my employer)?

I'm a school-leavers with exam ended at Nov 27 and wait 4 result which release in March 2009. I'm desperate 2 get a job n start work at Dec 1 2 fill out my time n earn some income. After a few try at various megamall I finally find a job who my employer is a women. She offer me RM4 per hr n work 4 4 hrs everyday n ask me when 2 leave. Due 2 desperation I say I leave at end of April despite unhappy with the income rate offered.However during Dec 25 I met my fren who work at another mall n he ask me whether 2 take up the job as the income offered is 2x greater than current n lesser working hrs. Eventually I confirm 2 him at Dec 28 2 take up tis job. I went n tel my employer. She is mad n sad. She say I broke my promise n I say I must move on 4 better payment. She cried n scolded me. I eventually get fired on tat day. Did I really betray her n is it right 4 me 2 break my promise in order 2 transferred 2 a better payment job?