Age is completely irrelevant, now in this day in age there are a lot of people getting married at that age and has been that way for some time now. Regardless of your age or being married if your with someone with or without a ring you still have committed to this person with all that's within you. If you cheat lust whatever all these things apply whether your married or not. You messed, up or did you? How much could you really care if you were able to be with someone else? Ask yourself that? People make mistakes, yes, but the are also greedy.
You will be prone to wanting to do this again everytime you see that perfectly round booty, I mean her beauty, or whatever else that may attract you to them. However it is what you do from this moment that will make the lasting impression. Expect her to not believe you when you say something, or tell her that your going somewhere, or even when you tell her how much you care about her. The trick is not only saying it but showing it more with your actions.
It sounds like you all need to have a nice long talk however painful it might be, that's what I would suggest to be the first step.
While overseas I saw so many of my fellow service members going through hell over there as we were, to only find out that their wife back home is screwing Sancho (that bastard) and taking all their money and leaving them with nothing. In fact, in 2003 after returning from Iraq one of my Marines killed himself because of this. So just think about things like this before acting impulsive or just stupid and think about what it will do to the other person.
Being drunk is no excuse and as far as what TOW said about it bringing out the real person that you are, I couldn't disagree more. If you would like to know the affects of alcohol then go and read about it, I would suggest out of a psych book. But don't ever blame it upon anything else except for stupidity or selfishness.
You messed up and if you care just try and fix it by showing her that she is important to you and you didn't realize this truly unfortunately until this ordeal.
Be real in life, say what you mean and mean what you say! If your not true and real to yourself then you will not be with anyone else. Take pride in being one of honor and integrity rather than one that is proud of having another notch on their belt. That's not cool at all.
WOLF