Looking for ideas on parenting and communication

My husband and I have two children. My husband and one of my children has ADHD. I am wondering if people on this forum have some good ideas about the following scenario which happens quite a lot in our home.

We really try to make all child-rearing decisions regarding scheduling and discipline together. We have pretty similar parenting styles, but we do slightly disagree in some areas. (I am more strict about standards for homework and cleanliness, but more lax about bedtimes and privileges.) Regardless of the decision, we usually talk for a pretty extended period of time about what to do and at the end of each conversation, I try very hard to sum up the decisions we have made so that there is no misunderstanding. Sometimes the kids are part of the conversation and sometimes they aren't. Regardless, afterwards, one or both of us goes to the children and tells them the decision. This process is pretty painless.

If the decision is something like whether a child can go to a friend's house or do something that is immediate, all is well. The result of the conversation is executed immediately. But, if the decision is about something that will happen later in the day, the next day, the next week or is a new family rule, we run into problems pretty quickly. In these cases, my husband often has a very different memory to the rest of us and he will often insist that a different decision was made or that a final decision was never made. In some cases, he even insists that he was strong-armed into making decisions. 

(A note on the strong-arming--I recognize that early in our relationship this did happen, at least from his perspective. We would have discussions for which I was completely prepared and for which he was completely unprepared. I am pretty quick at coming to solutions and he needs more time to process. For many years I did not recognize this and I would push conversations to the point of a decision before he was ready. I later found out that he often just capitulated due to not wanting confrontation. I have since realized that he needs more time and I have been working very hard to make sure the conversations go at his pace, that he has his entire say, that we break the conversations into several sessions if needed and that he is a part of summing up the decisions.)

Now back to the issue at hand--several times a week we have situations where we have told the children about a decision (we will go here on Saturday or you may have your friend over on Friday, etc.), but when the time comes to execute on the decision, my husband is suddenly balking. He sometimes wants to have the entire discussion over again (discussions which may have lasted hours over several days) and he gets quite irate that we are "pushing him". He sometimes wants to change his mind completely, throwing in new information or just switching gears. ("I know we said we'd go to the mall today, but I want to take everyone to a movie now. I mentioned that last week one time and now I want to go.") If I remind him of our decision and remind him that we discussed the movie and decided to do that on another day, he gets very upset and says I am mis-remembering. If all of us tell him this then he comes up with all kinds of theories, including that I have told the kids to tell him these things and that we are ganging up on him.

I realize that this (mostly) comes from a faulty memory of what was discussed and that he is truly confused in most cases about what was decided. (He mis-remembers other things in pretty shocking ways as well.) He feels defensive and upset, both because he worries about his memory and sometimes because he probably truly doesn't want to follow up the way we all agreed we would.

I am looking for advice on what to do about this. I have suggested writing down these decisions when they are made, but he really sees this as offensive and always says he "doesn't want it to have to come to that", what ever that means. In quiet moments he will admit that sometimes his memory isn't great, but he insists I am blowing it out of proportion. In the "heat of the moment", even hinting that he might be remembering something wrong is like setting a match to dry tinder.

I have found myself, at times, breaking promises to the kids just to keep things quiet. I hate this, and I think it provides a very unstable environment, especially for our son with ADHD. I have also found myself asking the kids to tell him what they remember, which of course is a terrible thing to do, although he believes them way more than he believes me. It is not fair to drag the kids into the situation.

I am looking for completely neutral ways to handle these situations and hope people here have some ideas!

Thanks in advance...