This issue will definitely haunt you for some time, if not, for
a very long time definitely.
I would come clean with my current bf about this if i were you, but
I don't think he's gonna swallow it well. Be prepared to take what
he gives. Its going to hurt.
But is getting hurt now and clearing the conscience better than
living with the guilt for time to come? This you have to
decide.
Good luck.