Should I send followup letter?

Got laid-off almost two months. I was interviewed last Thursday and the hiring manager told me that I should recieve the decision the following week, which is this week. Till now, I didn't receive any info about my status. The online application status was still open. This is a big company. Should I send a following-up letter to request my application status now, or just wait for another couple of days? Feel extremely desperate... I didn't think I did anything wrong during my interview. Thanks!