You need a good talking to, girlfriend.
You are off on the wrong foot already, and not because you didn't tell him the truth, but because you are already acting all pathetic and apologetic and YOU DON'T EVEN KNOW THIS GUY!
Cut it out! Be a strong woman, not a wussy doormat. If, by a small chance, this guy is good enough for YOU, are you going to give him all this power over you? Are you going to get all whiny and submissive and grovelling because you might have offended the all-powerful, all-important male??
You need to have some self-respect! HE should be the one kissing up to YOU, not the other way around. First of all, it wasn't his go**dam business how many fathers your kids have, and pretty darn rude of him to ask it on a first phone call. It is absolutely not his place to ask such a question; he hasn't earned your life story, and you are under no obligation to inform him. If you "lie," that's your right.
STOP APOLOGIZING. I can tell you right now, if you don't learn to have some self-respect and confidence, this guy is going to walk all over you, and the relationship will ultimately not work out. Any guy who likes a pathetic female only likes her because he can control her.
Your kids are depending on you. Get your act together. I don't know why, when you haven't even met this guy, you have already decided that he's going to be the one for you. You don't know one thing about him.
It would be much better for your kids if you focused on them, and refrained from bringing some jerk into their lives. But if you absolutely HAVE to date, then you need to make the guy WORK to EARN you, and believe that you are a prize to be earned; NOT that HE is the prize for which you must grovel.
Change your attitude, NOW. And if, after MANY MONTHS of dating, this guy turns out to be worth your time, and it's relevant to anything, you can tell him the story of your children's fathers. Until then, keep your privacy.
p.s. If he turns out to be worth your time, here is what you tell him when you finally tell him about your kids' fathers: "I didn't tell you earlier because it wasn't your business." And don't freakin' apologize.