It looks to me as if you have two (interlinked) problems:
(1) the way the business is currently run. You are overburdened and do not get the recognition you deserve;
(2) your relationship which is essentially one of parent and very dependent child.
The business one is obviously key. You mentioned that you need both your salaries to live on. That will presumably still be the case whatever happens.
I think you should consider, totally dispassionately and ignoring any personal relationships, what is best for you and for the company. I second the idea of talking to a good business consultant. Even one or two sessions will help you be confident in your decision and I think you know what needs to be done. I can PM you details of a good, reasonably inexpensive one if you like. I'd suggest you have support throughout this process either from them or from a coach of some sort because you are going to feel very alone and he is going to make you feel like the bad guy, which you are not.
Personally I think you should (a) bring on your best member of staff, not necessarily much more money, but certainly more responsibility and train them to take over the parts of your role you either don't like or which are easiest for them to take on. They should report to you. If you don't currently have one then recruit, even if it is part-time, as long as the person is good. There is a real wealth of under-utilised talent amongst women with great business experience but small children who have taken them out of the workplace who would be happy to work part-time (b) step forward in the way you deserve and take on the mantle of MD and the lion's share of the pay (c) move your H from MD to Chairman on a lesser salary (so overall the total remuneration has remained much the same, but has moved towards you).
Plenty of companies have a figurehead chairman who gets the title, leads board meetings etc but plays no active role and is paid a fairly nominal sum. That is where your H belongs. If he has some useful skills he should be pushed to use them in his role. If this would only be a part-time role, can he be encouraged to take up something else in addition outside the company? This could be something which will confer an indirect benefit like making him take responsibility for joining and participating in any relevant trade associations, or a different role altogether. He obviously does not enjoy what he is doing now and I suspect he knows that he is crap at it which is very depressing
Once you know what you want, talk to your investors, starting with the most sympathetic one. It sounds as if they will back you.
Then, and only then once you have protected your financial and business position, I'd tackle 2. Your relationship sounds dull and suffocating. It may well be over and I certainly don't think you should have sex if you don't want to, but I think it is probably too early to say since you have DC. What is clear though is that if you don't change things it is definitely over, so by taking action you are giving your marriage its best chance.
If it were me, I'd suggest that you start by telling him that the investors want the business change, its not a lie, they do. Then be honest and say that you want it too because you are the one who does the work and you feel that you deserve the recognition. Then go on to say that there need to be changes in your relationship too in order for it to flourish and go on to say what you are looking for which must, I think, include some independence for both of you. At the moment you can't have anything to talk about because you do everything together!
I'd suggest you agree to review things in six months, make it clear that this is make or break time, but also emphasise that the changes can be really positive if you both step up.
Sorry, all of that sounded terribly prescriptive and feel free to ignore it all, but I'm setting out how I would tackle it.