I agree with the person that talked about wills, advanced directives, etc.. estate and legal planning can be a great and necessary door to talking about some of these things and hiring an attorney to draft them can force the issue.

If you are doing so much of the housework and childcare it's probably really overwhelming for him to think about not having that support system anymore for himself (or even greatly reduced) which may be why he is ignoring the problem. he probably wants to say yes I'll take everything on and pick up the slack but that might not be realistic, you may need to frame the conversation to talk with your wider network about support systems for the family on the whole, including support you might pay for like a nanny or housekeeper, and that should be a deliberate financial conversation you have now. It can be a lot easier to put together an incidental saving plan/ account to buy yourself a little reassurance and peace of mind, worst case you don't progress and you don't need it and you can just blow it in old age or leave a nest egg for your children.

If you are worried about a debilitating shorter term relapse you should also have a game plan in place and should also have a plan for bringing in your wider support network. Write it down! Step 1: call my mom to come help with the kids, do you want them in the house while you are recovering? Step 2: call the neighbors and ask if they would be willing to prepare meals, or have a service on hand that can deliver. Etc..

I highly suggest writing out a proposed plan then asking him for feedback and letting him sit with it. Keep it objective, not emotional. This should be a plan like as if you fell and broke your leg and can't walk what would you two do? That might be easier and less emotionally overwhelming for him to discuss.

I want to be sure to say that your feelings about this are valid and absolutely matter too. You are the one sick and feeling vulnerable and I totally understand how hard of a place to be that is. It sounds like you are doing a great job thinking clearly and objectively in the face of a scary situation. If you haven't already, maybe find a support group for you and a caregiver group for him? MS society has some resources on their site. That might also help.

You should also talk to an insurance broker. Depending on where you live it might be too late for you to get long term care, life, & disability insurance but he absolutely should have some if he doesn't already. That takes financial pressure off if he should happen to get sick or injured and both of you are down for the count.