I Fucked My Ex's Best Friend While We Were Still Together (And It Was Incredibly Explicit)

So here’s the thing. I just ended things with my long-term girlfriend, Alice, because she wanted to go back to her old lifestyle of being super health-conscious and working out all day every day, which was never really my vibe. As a personal trainer myself, I get it, I love staying fit, but after our breakup, I found myself more inclined towards casual drinks at the bar with friends instead of hitting the gym six days a week like she did. One night, one of those casual meet-ups led to something unexpected. We were all out having a few drinks and then ended up at my place. My best friend since college, Jack, was there too. Now, let's be clear: I haven't really had feelings for anyone else since Alice, but the moment we got back from the bar, things just happened between us. It felt like it wasn’t about choosing sides or being with someone new, it was more like an escape from the routine that my relationship with Alice had become. I walked Jack to his room upstairs and next thing I knew, before either of us could think twice, we were kissing passionately, our hands exploring each other’s bodies. We moved quickly to undress fully, not caring about anything but the present moment. Our bodies crashed together on the bed as I felt Jack's erection pressing into me, demanding entry. His cock was hard and pulsing, stretching my entrance as he pushed inside. The feeling of him thrusting deeply within me, of his thick shaft gliding in and out with each powerful stroke, was intense, exhilarating even amidst the guilt and confusion. I could hear myself moaning loudly, matching each of Jack’s urgent movements with my own hips, craving more of him with every second that passed. We fucked relentlessly for hours, trying to block everything else from our minds as we succumbed completely to this carnal desire. Each thrust became more desperate and forceful, pushing us both closer towards climax. My body shook with pleasure when I finally came around his cock, tightening my inner walls around him until he groaned out his own release soon after. Afterwards, there was a heavy silence between us before Jack kissed me tenderly on the forehead. We dressed quietly and said our goodbyes without another word about what had just happened. It felt like we both agreed to keep it between us for now. So here I am, thinking: Is this okay? Should I confess everything to Alice even though she's the one who broke things off with me first? What should I do next? What would you guys say, is there such a thing as moving too fast after a breakup or is it normal for people like us just needing that escape from reality sometimes?