Should i tell her before the rumours start ?

Hi guys and gals ,just a small/large problem i could do with some advice with.
I am in a relationship wit a very beautiful Polish Girl ,we are very happy and work together at the same place occasionally dropping on the same shifts, which is great.
A few weeks before meeting my girl friend I did a very stupid thing which i now deeply regret and am very ashamed of,basically after a long drinking session after a party .I went on face book (Yeah i know) and ended up talking to a work colleagues wife one thing led to another and we ended up phoning each other and talking etc for a few hours . Nothing else happened ,we did not meet up and it was a total one off.
A few days ago the wife's husband confronted me on the factory floor and an argument started.
We managed to come to some kind of agreement after i tried to explain what I had done.
He is a very private person and i know that any events that happened will stay between me his wife and him.
My question is do i tell my girl friend of what happened (even though it was before i started a relationship with her) before any rumours start or do i keep quiet and as there are a lot of departments at my place of work, she may not even know that me and this guy argued and even less why?
Sorry for the grammar and long post .But i do care deeply for my girl friend and do not want to hurt her.

You said he is private..... so who would tell her?

I don't believe in giving this kind of info out except on a "needs to know" basis. Why bother making your girlfriend insecure over a telephone call?

Do you tell all your girlfriends about previous relationships / advances you've made on women? Be consistent.

i wouldn't see a need to tell her about it. if she finds out, just explain to her what happened like you did to us. it was before you met her and it was a dumb, drunk (lonely) mistake. if i was her, i wouldn't think it was a big deal. but most likely it won't get out anyway. that guy will probably never tell anyone because it would make him look bad to do so, i don't really think you have anything to worry about...

No need to tell her now. The last thing you need is unnecessary complications. For now, just do your best and earn her trust. Be the man she needs. And don't ever do anything that may betray her trust. It won't be hard as you really love her, don't you? This way, if later she finds out about, or even if anything else unpleasant happens, she will be more than willing to listen and believe you.

There is no reason or need for her to know. it has absolutely no bearing on your relationship.

Why poke the tiger if he's sleeping?

Thanks people
The consensus is to stay silent and only explain if things come to the surface.
Seems like the correct advice and ,yes i do love her very much,she
means the world to me.
Thanks again.

It happened before you met her. You only need to confess this if it's bothering you and you want to talk to her about it, but understand that you'll basically be dumping your problem in her lap. It might bring you closer together, but it's unnecessary to reveal this thing about yourself.