I feel so guilty..

I went to my bf's house last night and was at his house today until 6pm. I got home to my mom calling an ambulance because grandma fell at 4pm but no one was home to call. So when mom got off work, grandma had already been laying there for 2 hours. She busted open her arm and was covered in blood laying on the floor for 2 hours. What was I doing at 4pm? I got laid, got stoned, and my guy made me waffles. I feel so fucking guilty because if I had been home earlier she wouldn't have had to lay there so long with no one to help. She's on blood thinners. Could have bled out. Thank God she didn't...but I feel like a horrible granddaughter for not being home to help her..