i hear you on those troubles. while i haven't entirely experienced that extent, it can be difficult to dig yourself out.
first, though, i would budget for and consider getting professionals for most of those jobs. obviously, you can't do it yourself and you and DH combined aren't motivated to do it. so pay someone. the job gets done, someone gets much needed work, and you both are happier.
second, i could go through this process in this way:
A. having a cleaning/decluttering party--tell friends and family that you are desperate for their help, but will make the process as painless as possible by making it a party. food (breakfast, lunch, dinner, and snacks), funny/stupid games with prizes, contests with prizes.
people come and you have donuts and coffee, an ice breaker, and then draw names to create teams. each team is given a room, and one team is assigned to help you with the decluttering.
the first step is that each team is given boxes for their room. anything on or under a surface is put into the boxes and brought to you to declutter with your team. the first team to get their room emptied gets a prize.
then, they go to clean their rooms, while you and DH declutter every box. your team will help you divide them into keep, donate/sell, and toss (recycle/trash).
once the rooms are clean and you have decluttered, everyone is done with teams, and so you reassign. these folks will take things to donation, those folks will take pics and put ads up on craig's list and the like. others will prep things for trash/recycling, and then still more will help you organize what you plan to keep.
finally, when it's all done, you have a real party! food, drink, fun, and of course, prizes for "miss congeniality" and "best sweeper!" and so on. celebrate the accomplishment.
B. After this cleaning party, get the other work done as time and budget allows. find and hire good professionals and work your way down the list. you might notice that as things get done, you'll both be more motivated to do what you can do, and what you can't still gets done.
I would start with structural things first, then carpets (i can't stand bad carpets personally), and then walls and then furnishings and what not. this is just an order that makes sense to me, but it will work.
and while it may take years to get everything perfect, it's ok. you'll feel good in the process.
It can be done and you'll be ok.
it will just atke some time and elbow grease.