That was the stupidest answer possible. Sorry, but don't take that advice. No good ever came from 2 people staying together for the kids. If he's down to play dad again, good for you. But that doesn't mean he wants to be with you anymore. If he wants nothing to do with the kids, why would you want him there anyways? Regardless, you can't force a round peg in a square hole. Maybe it's just over.
And as far as keeping it goes, that is your decision. Don't let some stranger who knows nothing about you tell you how to conduct your personal business.
It depends on how many weeks you are pregnant, if it is already 20 weeks plus then chances of termination of pregnancy is difficult, but take some Obs/Gyan opinion and then think of the termination of pregnancy. Yes Mr ScottX0706 is right he has already made up his mind to leave you.
I would suggest not to put him on the birth certificate if he has not made a decision by the time you bring your beautiful child into the world. If he can not support your choice, and is a negative influence, then this could be an indication of his lack of commitment to your family. Sometimes though men feel nervous about the whole thing and just need a wee bit of time. If he is a good father already then remind him. He could have a confidence issue.