J.S.
I don't think it's EVER a good idea to make a decision like this knowing full well how your husband feels. Even if he does sound like a controlling pr!ck. In the other instances, having a baby and inheriting a cat, those were things that "happened" and you dealt with them and were happy with the results. This is different... this is choosing to make a 20-year commitment (since many cats live that long) for a pet that you know your husband is opposed to. That's just not right.
We have a beautiful 9 month old cat, which my children and I discussed with him repeatedly. He agreed at the time that he was ready. I'd love to add another cat to the family, but he's vehemently opposed. We discuss it, and I tell him that he doesn't have to speak at all, just listen, and let him know that it's important to us. But I will NOT go behind his back and "just do it."