All memories are things in your head. And those things in your head are real things in your head. But that doesn’t mean they are or were real things outside of your head.
The labels you stick on the things in your head are under your control. If you choose to get into judging and discriminating between memories because you want to be certain about whether you did something or not, you’re setting yourself up for ruminating and worrying. It’s helpful to accept the stuff in your head as stuff in your head. Trying to put labels on that stuff is only going to lead to more misery. The problem here isn’t about knowing whether it’s real or not, the problem is the desire to know if it’s real or not and believing that you can somehow discriminate between real and unreal things in your head. That would be like trying to discriminate between good clouds and bad clouds. They’re all clouds.
Check out this video on “False/Real Memories”: