My Deep Secret with My Sibling's Partner

I’ve been keeping a dark secret for weeks now. It started when my sister’s partner came over and we got tipsy together. One thing led to another, and I ended up in bed with him, both of us completely naked, our bodies intertwining without hesitation. His hands explored every inch of me as his tongue traced the curves of my body, leaving no part untouched. We climaxed together, tangled up in sheets and sweat, the pleasure overwhelming yet tinged with guilt. Is this something normal to experience? Should I tell anyone about it?