I have that issue with my son and his bio-father. It's not a popular stance (the whole united front thing), but I just call them as I see them. When my son is out of line I say so, and when my husband is out of line I also say so. And when they're BOTH out of line, I also say so. I hate it, but I'm married to a toddler who doesn't care about childhood development, age appropriate behavior, or restraint (aka, being the ADULT in a situation).
If you're lucky enough to be married to someone who listens and respects you, I would talk with your husband in private so that you don't have to call them as you see them, because his behavior will change.
My H gets mad at me for not backing him up, but I REFUSE to back him up when he's wrong. Only children and pets can be abandoned. Everyone else can take care of themselves. If my H doesn't like being told that his tone was hurtful and uncalled for, he could STOP saying things in a nasty tone of voice. But my son is a CHILD, it's my responsibility to look out for his best interest and to TEACH him. I will not abandon my child just to keep my H from having his feelings hurt.