That wasn't to kill herself though, that wasn't why she did it. Jean found the bi-polar pills that Stacey claimed to be taken but was hiding over a period of time, Jean found them and as they were in the heat of an argument said she needs to take her pills to get better, typical Stacey done that by having them all at once but the intention was never to kill herself but to so her mother she was taking them and everything would be fine, as Jean believed, Jean made her chuck them up as the amount would be damage to her.