I guess it is too late to say use a condom? Which is what you should have done in the first place. I mean, granted, you took your wife's word for it that she didn't want another child yet, but she said yet, not never.
So instead of hastening the process and getting another girl pregnant, you should have just waited for your wife to get to the point where she was going to be ready to have a baby. But here we are, paying for your selfishness.
For one thing, listen to your wife the next time she tells you something. For another thing, it's time to pay the piper for the things you've been doing in the dark.
Tell your wife what's going on, because that is literally your only option at redemption at this point, unless you plan on being a deadbeat dad. Then, figure out how you are going to support the two families you have created.
The only one paying for the consequences of your action should be you. Don't take it out on your children. You haven't been an honest man before – it's time to get a job and be a man now.
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