my little brother desecrates shabbos and i need to help him stop without getting him in trouble

i come from a very frum family of chabad, i am 14

yesterday shabbos night after everyone except me and my brother (9) went to sleep and he’s downstairs while im reading a book, i go downstairs and catch him on his ipad. he starts crying and says he cant stop himself and that he’s been doing this since sukkos, and i who was fairly tired promised that ‘d help him stop and also not tell our parents about this, problem is. im not sure i can do both, i always go to sleep very early on shabbos with this as a rare exception. and it’d be REALLY hard for me to change this, so id want to turn to someone who isn’t like this but i promised not to tell my parents about it. what do i do in this situation?

edit: i have decided on hiding it from him before shabbos, thank you to u/meliorisms u/shinytwistybouncy and u/BloodDonorMI for the suggestion