One of the interesting things about life is that it can present us with the fact that what we thought we knew absolutely about ourselves is wrong. Well, sometimes it's not so much wrong, but it turns out what was right for one phase of our lives, may be the opposite of what we want for another. I know there are many happily childfree people who have never wavered in their conviction. But I've often written that I think it's a good idea for people to test their certainties -- especially when it comes to having children -- so I've heard from many people who knew they never wanted one, who then ecstatically send me pictures of their babies. Ideally, when you realize something you were certain about no longer is true, your partner has made the same shift, or is open to exploring it. As you are experiencing, it's wrenching when this isn't the case. More than that, biology sets a deadline and forces you to make life altering decisions under pressure. You know that if you end your marriage in the hope you find a partner who wants children with you, you may not find this person.

Yes, you are trying to change a fundamental understanding of your marriage, but I don't think it's fair for your husband to simply shut you down. Tell him this is so important to you, and you feel so stymied in getting him to listen, that you want the two of you to go see a counselor. At the least that will help you clarify your short and long-term goals. If he refuses to go, and refuses to explore this with you, then that says something profound about what kind of life partner he is.