Curious Son

My nine year old son keeps touching my breasts. It has been happening for a while now. Most sources told me that is a normal phase with boys growing up, though touching, and so often no less, might be a bit concerning. I told him to stop multiple times, and he would stop for a while but soon enough he was back at it. I thought about grounding him, hut it would break my heart to see my sweet little boy sad. Finally, I offered to show him my boobs, but only of he promised to stop touching them. He eagerly nodded. And so I did. I simply lifted my shirt, I don't wear bras in the summer. His eyes nearly bulged out and he had this big goofy smile on his face. I saw his little hard-on tenting his shorts, and I creamed my panties. That was last week and I've been masturbating to it over and over again since. I'm a horrible mother.