Hello Cam82, and welcome to the forum.
Many, many of us understand this! In fact, sadly, it probably is more common that truly supportive spouses.
All you can do is try your best to get your husband to understand. Maybe even show him this thread.
The thing is that fibromyalgia is a difficult thing to understand because the person can look completely robust and healthy and be in constant pain. The person can be going strong one day, able to hike up a mountain, and on another day be unable to get off the couch. The person can be thoroughly intelligent and together one day and forgetful and feeling stupid on another day. It has nothing to do with choice or being "lazy".
All of these things describe me, personally. And I am a person who is dedicated to managing it the very best I can from day to day and I have had it for years and have learned a lot. Someone newly diagnosed has it much worse at first.
It's unpredictable. You don't know when you make a plan whether or not you will actually be able to do it the day it comes, and people think you are flaky if they don't understand what you have to deal with. People who truly love you will do their best to understand and to trust what you say.
Sadly, some people choose not to believe what we say we are experiencing. A person will know someone for years, know them to be trustworthy, and then not trust them on this. It's very disappointing. Personally I think it comes from fear. If they think it is a myth or that you are making it up, then they don't have to deal with the fact that fibromyalgia can strike anyone at any age, including them.
There are thousands of people on this forum. None of them would have chosen this if they had the choice.
I suggest you sit down with your husband and tell him flat out what is going on for you. Explain that a person with diabetes usually looks healthy and like everyone else, but they have to deal with their illness or die. Tell him that you have an invisible syndrome also, and there are many invisible syndromes or illnesses. Which doesn't mean they don't exist.
He needs to be supportive of you to the best of his ability, just as he would expect you to be if he were struck down with chronic pain and other symptoms that make life difficult.
I don't know what you mean by "rubbing your face in it" but that doesn't sound very nice. Ask him to treat you as he would want to be treated.