Quoting Alissa McKeighan:" There's always adoption. If you can't emotionally handle another abortion, I would strongly recommend ... [snip!] ... than their parents' divorce... Such as having an emotionally traumatized mother and a disrespectful and unsupportive father."
And if he Thinks it's going to be Expensive with a 3rd Child in the Home, is He in for One HELL of a Wake Up Call when he realizes how even more expensive it's going to be, when he's Paying Rent & bills for himself, PLUS separate ones for 3 Kids(& possibly spousal Support)!
You're probably in a position right now where Your Relationship isn't going to survive either way if he's That Adamant. Because You are going to find yourself Leaving Him for the Abortions, or he's leaving You for Not having an abortion. I hate to say it but it sounds to me like he's just looking for an Out, or a Completely Self-Centered Insensitive Ass.