Drawing a line under something and getting over it, that's the common advice.
Nobody says where to draw this line. It just says that it has to be there, somewhere.
Nobody says what to draw this line with but I guess it's not a pencil.
A pencil's easy to erase, a line under something has to be forever. It's something that should last. A felt pen doesn't seem to be right either, it might extrude, so you might fear to draw a line under things that lie under the actual thing, to draw a line under things you didn't want to draw a line under. That's confusing.
But even though it's confusing, I draw lines under things a lot.
On the underside of my forearm with a razor.
Red, wide lines that remind me of what was and what is, of what I should forget and what I will never be able to forget.