Bin the photos Spider, if they're going to trigger bad memories. The human brain isn't meant to remember everything and forgetting bad things is a blessing. If you never think of these people and never look out those old photos from time to time, then you don't need them.
Hire a cleaner and pay for it out of the household bills account, Ellie. He's literally ignored everything he could ignore. And still is, when it comes to home life. Do what men always do and milk the illness, since he's not playing fair. Clear out the under stairs cupboard and telly him you're too tired to cook dinner so he'll have to. Then leave him the washing up too.
You've got time before July to do something about the house. Gather actual rubbish and bin it. Don't waste time recycling it unless it can go into your kerbside pickup each week. Bag/box everything looks messy up and just shove it into a cupboard/spare room/under the bed. Don't worry if it cramps his space or inconveniences him in some way. I presume it's not solely all your stuff? Get the cleaner back again for round two once the place is clearer, claiming fatigue after decluttering on top of flu recovery. It's not as if he's going to help you deep clean so just make sure it comes out of joint expenses.
Do not help him look for anything he can't find, he'll have to clear out a bag/box (and deal with the contents) until he's found it. Just shrug like hell does and say you've no idea, when he inevitably asks where xyz is. If something is bagged/boxed for 6 months or more, don't ask him if he still wants it, he hasn't missed it in all that time or gone looking for it, so just get rid of it. I know I sound harsh with what I've said, but he doesn't deserve a medal or special treatment for doing the bare minimum whilst you're sick and slacking off on his share of household chores the rest of the time. Helping a mate when your own house is a shit tip and you've guests coming is a massive piss take.
Don't compare yourself to your sister though, maybe she has more money than you for cleaners etc, maybe she has a more helpful DP and life in their house is more equal. One of my ex's took up so much of my time because I was always cleaning and clearing up his messes, he did nothing much being too lazy. I added it up once out of pettiness and when I left him I had 7 1/2 hours back per week, because I clear up after myself as I go along. That's how much extra work he created on top of what I'd usually do. Your sister loves you and knows your house and she's returning, so she can't be that disgusted by it 😅
Two moisturisers used up
One unflattering pair of leggings donated
One pair old bobbly socks recycled
Total is 4715