I'm so sorry you're going through this difficult time. I agree there are probably underlining issues and it isn't just about the breastfeeding. As you've said yourself he didn't really want to have another baby in the beginning and didn't bond with her until after she was a year old; could it be that he resents that you didn't have the termination in the beginning and almost feels like you've made this decision on your own and now you should deal with the consequences (ie looking after all 3 children?). not to say he's being reasonable of course.
I believe you really need to talk about your feelings, but with a mediator. You can't keep ignoring the obvious and let it go on.
my DH felt very similar to your DH when I was pregnant with my 4th. It was very unplanned and we hoped to be in a better financial position as I would be able to go back to work. He's said many times how much better off we would be and I completely agree but he agrees it is what it is and has said he could never imagine not having our newborn. That being said I don't ask for help because I feel like I should manage. I do of course have days when I need a break, but I look to friends for help instead. Could you do the same? Even if it meant play dates over the holidays and you're just with your 2 year old at an indoor play centre with a friend having a coffee? I really find that's my best release.
I hope things get better for you. Try to talk to your husband at a time when youre both happy, and try not to bring up feelings etc during an argument.