All Eyes on Me

What Elizabeth said. Your mother dying is a reason, not an excuse. Also: grief - which will happen and likely is right now - produces cognitive deficits, and you can't perceive that they're there except in a vague sense of "hm, why am I slow on the uptake/forgetful/etc.?" It's not that you're suddenly becoming stupid, it's that grief is chewing up a lot of your functional capacity.