Thank you so much for your advice! It is highly unlikely that my boyfriend would find out. When I spoke to the 'other guy' the next day, I told him I was thinking of telling my boyfriend and he said I shouldn't. So I really don't think he'll be telling him either.
Anyway, I think I have decided there is too much at stake if I tell my boyfriend. Not only the hurt it would cause him, but also I live in quite a small community and there is quite a lot at stake for the other guy too. Other people would get hurt if found out. I suppose my main reason for telling would be to have my own peace of mind and not to feel guilty when my boyfriend treats me so well.
I've seen a priest and confessed everything. The priest's final words to me were; 'Be at peace with yourself'. If I can do this, I think I could see a great future with my boyfriend. What I'm terrified of, is that at some stage down the line, (maybe a month, a year, 5 years) that guilt would return or a conversation about loyalty might come up and I would end up telling my boyfriend then. And of course, as bad as it would be now, it would be so much worse down the line. My friend said if I can't live with the guilt, then break it off but give a different reason for it (since over a month has passed since incident). But I would hate to think if that happened, that my boyfriend would think it was off between us beacause of him, when really it would be me.
Of course there's the possibility that I can overcome the guilt and within a few months block the whole thing out of my head and move on with my boyfriend. I have decided I'm giving up alcohol for Lent too (and possibly longer) , as I realise how badly it affects me. Sorry, that's a lot of information! Can I just ask you personally, do you think it is deceitful of me to try to carry on as if nothing has happened? One minute I think it is selfish of me to tell so I can clear my conscience and the next I think it is selfish not to tell.