Interview...cont

Today i make a wrong decision, i shouldn't accept the job so fast, now i regret, what should i do? I know this is my false, a big big false, the post at lowyat is really not suitable for me, not only the parking problem but the working hours, it's too long, and now what should i tell to the manager that i wana reject the offer?? she probably will think that im jus playing around, not serious, a bad comment sure will come out from her mind, but honestly, this is my false, i know, but i don't want to wait until i work inside there only say regret. Can someone tell me that what should i do, i wana reject but i think the manager sure will scold me like hell, oh god!! what should i do? should i call her to tell the truth or make a story to her?? im not dare to tell a lie, then? 5555555~~~ help