Hi J.,
Congratulations for not accepting that behavior in an any adult, especially your husband.
It's aggrivating and downright undermining when your spouse trains your child to do more damage and won't discipline himself or her.
I can say a lot, there are many aspects of undermining behaivor, some of which could be that he just plain has no courage or skill to discipline a child because he doesn't discipline himself very well, he's afriad to try because it's so unfamiliar on both sides (people who dont' discipline themselves well are usually pretty odd at disciplining children and can do some real damage) and he doesn't understand the severity of what he is doing both to you, your marriage relationship, and to your child by being a child instead of an adult role model, teammate and authority figure.
The best reference I know on "Just what exactly can I do that works to address this, how do I keep my perspective healthy through this mess, and what do I expect for a response from a person like that" that is short and to the point is a small book (100 pages, big print) by a man named Carter, who went through this and helped others get through it. Undermining people show up when you least expect them, and they can be maddening to deal with when you want to keep giving them the benefit of the doubt that they will REALLY THIS TIME NO FOOLIN HONEST STRAIGHTEN UP AND COOPERATE.
The book is a small one, still in print, titled, (of all things): "Nasty People, How to Deal With Them Without Becoming One Of Them". It recommends a lot of specific things to do, say, how to approach the behavior, just a tiny bit of theory, understanding, hilarious, brief and right on the money with every situation I have used it. I looked for years for this kind of guide to dealing with saboteurs for a long time. I was afraid I was going to have to write it for myself I was so frustrated dealing with this undermining stuff.
And it helps that Carter dealt with them himself, nearly drove him nuts and he wrote this because there was no short, effective guide out there. It also helped that he is a PhD Psychiatrist, who was at his wit's end dealing with a real case in his own marriage. I will look him up and send him a thank you, it's been nothing short of amazing.
In my searches, I found and I also use an earlier book, Crucial Confrontations, for people who are behaving badly, and The Magic of Thinking Big, to keep myself focused on behaviors which will hold me accountable in my own life to reach my potential, both have lots of templates, examples, and are best sellers and proven references.
Blessings to you J., and I'll be happy to disscuss any of those books with you if you want more info. They are pretty dog-eared now, with writing in them, so have been very good for me to learn from.
M.