Well my father used to steal from her, and my grandfather, and from other people. Now he is prison. I am only 13 years old, and my mum unconsciously gave me his responsibilities (paying bills going shopping) hence she gave me her bank details. So it started off with small things. Buying with her card, and then I started stealing larger amounts of money from her bank account, and started lying about it. Now I lie to her, and all of my best friends without thinking about it. And now I feel so bad about it.

Help

u have a best example in ur life and that is ur father.
if you follow him finally u will be landing as a prisoner.
so better keep that in mind first.
first talk to ur mom and explain her under wat circumstances u did all those.
try to convince her first and jus keep in ur mind that u will be a prisoner if u continue all these.
and this is not an addiction. since u wer not caught u think u wont be caught and u are lying ,stealing. jus think abt the situation u have to face if u were caught. since you are too young jus try to stop all these for 1 month later u wont feel like doing all this. while going out take someone with you so that u wont try to do this in front of others.

Your lack of honesty, maybe a learned behavior, can best be overcome by acknowledging the truth to your mom, and others, and admitting your mistakes.