If this is true, you're a cunt, and I hope your girlfriend leaves you, she deserves better than you, saying "There's no ring on it yet. Look, I know this may come off a brash, and it's certainly fucked me over, but until there's a ring on it there's no solid rule of law that says I can't mess around a bit before I settle down." is completely disgusting of you, what the fuck is the point of being in a relationship if there's no commitment what so ever? You may as well just fuck random girls without calling yourself someones boyfriend, I am personally glad your dick has caught up with you, and dropped you into a load of shit, and for the record, the "I was drunk" excuse is terrible. You're also pretty selfish with your claim that this will "ruin your life", have you thought about how this girl feels? Or how your child will feel? Seriously man, you've fucked up big time, you deserve no sympathy for your actions what so ever, and it's time for you to tell your girlfriend you've fucked up, do not come and ask us how you are going to get out of this, you do not deserve to get out of this.
Also, yes, you've pissed me off to some degree, I'm not overly sure why, but you've succeeded in doing so.