Dear avodas.hakodesh (whatever your real name is, really),
First of all, congratulations on your 40 days clean! It's a great brocha that is rare for people who fall a lot. You are so fortunate! Hoping you see and know that and will not forget. Now about your dilemma:
If you see so clearly that it is just a mind trick, then you probably saw it then, too. So why'd you do it last night if you really knew that it was just a 'mind-trick'? And if you say you did not see it then but just see it now, then mimahnafshach what's your worry? Next time you will know not to make light of sinning just because of something you read somewhere, no?
My real point, be"H, is this:
If you have been falling pretty regularly but stayed clean for about 40 days which is very unusual for you, then it may be more likely that you fell not because of something you read somewhere, but simply because that is your habit. Looking elsewhere is not always wise. Habit is more powerful than your seichel, twists the seichel, and often the cheshboning we do to 'figure it out' is just hevel ur'ayon ruach.
Now, if it is not your habit to fall every few days or weeks, then it's something else. But what are the facts here, chaver? You can get that clear here first. It would help to see whats going on in a bigger picture.