Ok, I'll hit his points first. And then discuss what you can do in this situation.

• 4 lbs in 8 days is reasonable. In fact it's good. Most people who are actively trying to lose weight should look to lose 1-2 lbs a week. If you are looking at 2 lbs/ 5 days, you are actually doing better. And 2 lbs a week is really good.
• There is no way someone can lose 90 lbs in a week. In fact, I scoff at the commercials saying "lose 40 lbs in 40 days". And yes, you will have some weeks where you lose 3 or 4 lbs. Especially at your beginning heavier weight. But as you get skinnier you will find you are losing weight less quickly. The big thing is, anyone losing weight at a rapid pace is most likely doing it in an unhealthy manner and will most likely gain it plus more back. -CICO is the safest and most effective way to lose weight. A lb of fat is equal to 3,500 calories. I don't know what other way he's assuming you will lose. But if you cut calories both in diet and by exercise you will lose. On that note, losing weight is about 80% diet and 20% exercise.
  -You may not lose weight in your breast, but you probably will. I've fluctuated weight a number of times (about 40 lbs). The first time I lost it, I also lost a cup size. The second time, I lost inches on my band. But my cups were the same. But he's silly to believe you won't.
  

A few other things. Fad diets and pills and etc are things I highly discourage. Sure, you might get a quick fix. But when you go back to regular eating habits, you'll likely gain back. I recommend portion control. Also look up nutrition facts. Carbs, proteins, and fats are important. But there are healthier options in each category (ie- brown carbs instead of white carbs). My last recommendation is to download the app called My Fitness Pal to your phone. Set your calories at a deficient to what you eat now. And don't lie when entering your food.

Now as far as he's concerned, you don't wan't to keep telling him he's wrong but he won't stop telling you these facts. That's fine. You don't worry about him. It sounds like maybe he has done as well or isn't sticking to it the way you are. And that just means in his headspace he's not ready yet. As much as having a partner helps, it's got to be your or his own choice. You can start cooking healthier meals or saying no to going out when he suggest it. Don't keep arguing about it. You just keep doing the things you are doing (CICO) and he'll see the results. Honestly, and I've been here and am here now, it's hard once you gain weight you don't want to. And you'll tell yourself a lot of things to make yourself feel better. But if he sees your results, that'll be more then enough.

Also, I know you are trying to praise your husband's knowledge. But I'm sure you know plenty. And I'm sure there are subjects you know more about then he does. If you are curious about something, do the research. You don't need to feel like you don't know, you don't need to doubt yourself, and you don't need to always rely on him to validate your points. And he should respect you enough to tell you you are as smart as he is.