You haven't been clear on whether he knew about having a kid or not. That's the only thing that could possibly clear him of charges at this point - although it's extremely unlikely for a guy to not know. The girl would have to get pregnant, and instead of telling him about it, she'd have to break up, break off all contact, and then somehow make sure he doesn't learn about it via third party (such as friends, family, etc.). Having a kid is not an easy secret to keep, pregnancy tends to attract attention, and people usually ask questions, and then there's internet/facebook etc.
So I'll just assume he knew and didn't tell you. So he's been deceiving you, lying to you the entire time. Wow. And now he's got you wondering whether you're a complete bitch or not? What an asshole.
If he's had a kid for 15 years, it's high time he took some responsiblity. But that's his responsibility - not yours.
Time to move on. Better a horrible end than horror without end.