Okay, so I know when to "but I digress"; I use it when I'm talking about something and then stray off topic and talk about something else, so in order to get back to the topic, I say "but I digress".
But the dictionary says that digress, a verb, means "to stray off of something, to wander from a path, or to turn aside, etc.". So when I say "blah blah blah, but I digress", it's like I'm saying "blah blah blah, but I stray off topic." So when I say that, do I mean:
blah blah blah, but I'm a person that usually goes off topic, so let's get back to the main topic.
Or do I mean:
blah blah blah, but I'm straying off topic, so let's get back to the main topic.
I'm pretty sure this (the second one) is what we mean when we say "but I digress", but shouldn't the correct English be "but I am digressing" or "but I digressed"?