Right, so the tree line detail is what gets me with this. When something is hovering just above the trees it usually means it's using them as cover or reference points, which rules out most conventional aircraft in my experience. I've been chasing these things across Bodmin Moor for the better part of two decades and that specific behaviour - staying just above the canopy rather than higher up - comes up again and again in the accounts I find most credible.
What we really need from you is some measurements. How far away was the tree line roughly? Could you make out any shape or was it just light? And most importantly, did it move at any point or just sit there?
The "can't stop thinking about it" feeling is something a lot of people report and honestly its one of the more interesting aspects of these encounters. Whether thats psychological or something else entirely is a whole other conversation.
Post whatever details you remember, even the ones that seem daft. Those are usually the most useful.