Obviously, that way of talking to you is unacceptable. Just. not. ok. But I'm curious. Is this how you guys normally interact? Did he always talk like that to you? Or did this just start since you got sick? And did you talk like that to him before (fighting dirty, name-calling, hateful words), but have decided to change and have been trying to do things differently lately (I only ask because you said how careful you've been since you got sick to be nice)?
I think one thing is absolutely clear, and that is that the way you are describing your relationship just can't go on--it's not healthy for anyone involved, especially the kids.
But, depending on how your relationship has developed, etc., I think the solution might be different. If he's a chronically verbally/emotionally abusive jerk who has you on tiptoes all the time (which is kind of what it sounds like), there may be no saving the thing, and you and the kids are honestly better off without him. On the other hand, if you guys have a pattern of explosive fighting like this (you can dish it out as well as he can), then maybe what you need is some couples therapy to learn how to better resolve your conflicts--I have a dear friend in a relationship that was like this, and it took them years, but they have finally purged most of the toxic interactions from their marriage, and it is a much healthier environment for all of them, including their wonderful daughter. Finally, if this is a recent and drastic change from the man you married, you might want to see if there's some explanation for the behavior change (medical issues, drugs, psychological issues, etc.) before you decide that it's over. A loving, two parent home is best, but a loving single parent home is FAR better than a toxic two parent home.
As for the abortion, that can only be your decision. I would NOT do it because he has demanded it--i.e., in order to please him and "save" the relationship. I would venture to say that if you have an abortion now, for that reason, you will NEVER be able to forgive him or yourself, and the relationship will be truly doomed. The ONLY reason I would consider it is if you think that the relationship is too far broken to save, and you are leaving him, but you don't think you'll have the means to care for the 2 kids you have, much less a third. That would be a very scary situation, no doubt. Even then, I really don't think I could do it, but that's an individual decision.
I feel for you. You're in a scary place. Right now, if you can, it sounds like getting either your husband or yourself and the kids out of the house temporarily would be the best thing, so that you can be in a safe and sane environment while you figure out what your next step should be. Since you're so sick right now, I think staying with parents or someone who could help take care of you and the kids is an attractive option. If that's not possible, I'd at least try to make it clear to him that his words to you were utterly, totally, and shockingly unacceptable, and that you don't intend to interact with him until he can approach you with more respect than that. I would NOT apologize to him if you really don't have anything to apologize for, but I would cautiously accept his apology, on the condition that he agree to therapy if this is a recurring thing, or, if this is a very rare/first-time thing, with the warning that any further such violations will not be excused with just an apology--that there is NOT to be a repeat performance of such disrespect.