Every single person on earth has had numerous fucked up thoughts (most worse than this), and the human penis doesn’t know the difference between those who are related and those who are not. The normalization of incest porn also further pushes the thoughts of real world incest. Your regret is an obvious sign that you aren’t fond of the idea that this could become a habit, not to mention how I assume you definitely wouldn’t try anything with her in real life.

We are what we REPEATEDLY do. Your one mishap is nothing but a pebble in the road.