Started a new relationship a few months ago, after a few dates together I (very stupidly) slept with my ex - I have no idea why, I have no feelings for him and have no intention of getting back with him.
At the time I hadn't slept with my new partner and confided in my friend, she said I shouldn't mention it as; it was a mistake - it wasn't strictly cheating since I'd not yet slept with new boyfriend - wouldn't happen again and would give him the impression that I still have feelings for my ex, so I didn't say anything but now I have really started to fall in love and feel a bit wrong that I lied.
Should I tell him and risk losing him, or keep it shut and hope the guilt goes away?