I once accidentally left the oven on for 7 hours straight and my mom never found out
Did you forget to turn off the oven? That must have been a relief that nothing bad happened.
Yes I forgot, I felt so relieved and happy.
I know you feel relief that your Mom didn't find out, but that was a dangerous situation. A fire could have started and leaving the oven on for so long is a big waste of energy. You should tell your Mom and discuss with her ways in which this could have been prevented.
I'm not talking to my mom about this, I plan to keep this a secret from her forever.
It seems like this was an honest mistake, but please make sure next time to turn it off or to be around the oven when it is being used. You should learn to monitor your oven closely and remember to set a timer next time so it turns off automatically.