I think the important thing is not to fight about it in front of the kids. They´ll use it against you. Talk to your husband and agree that you will discuss these things after the kids are down for the night. Sit down at the kitchen table with no distractions and tell him really briefly (short attention spans!) why you feel that it´s bad for the kids (note, not YOU) to have their parents sending them mixed signals. Ask him to back you up when you set a rule and you´ll do the same for him . . . in the moment.
My husband and I face similar issues. He was abused as a child, so he feels that no discipline is good, not even time outs! On the other hand, I don´t want my kids to grow up spoiled brats. So, he just lets them do whatever they want and "tattles" to me so I can be the bad guy.
We´ve had a lot of discussions about this and have come to agree that we will present a united front, at least with the kids (and argue about it when they are gone or in bed). He agreed to this after seeing that our 2 year old threw massive tantrums with him every time they went to the store together. When I went with them, I gave Dorian a Look and he calmed down and started pointing out different things in the store. My husband was amazed.
"How come he listens to you?" I just told him that it´s because I don´t give in all the time. Novel concept, huh? My son, at just 2, has already figured out who is the disciplinarian around here!