Child scared of everything

[Potter10]

I'm absolutely at my wit's end. I have a 10 year old son scared to go out of the room on his own, he won't go to the bathroom without someone going with him. He won't do anything alone in our home.

My 8 year old son is worse then him at night, literally crying and battling EVERY night. I lie with him, talk to him about things we could do tomorrow, read a story anything to keep his mind off being scared before sleep then leave the room and instantly he's crying. I go back in countless times before I just can't deal with it. I sit in the landing between both their rooms so they both know I'm there. My 6 year old is in the same room as the 8 year old and goes to sleep pretty stress free most nights. The 8 year old is up and down throughout the night.
I've asked them what it is they are afraid of, I've talked in depth on numerous occasions to reassure them there is nothing but good in the house. I've explained every possible noise they hear every possible worry they have I've addressed but I'm so tired and drained and sick to the god damn last bit of tether that I have. I CAN NOT cope with it anymore. God help us if there is a slight wind outside because you'd think it was a hurricane about to blow the house down the way they scream.
The 8 year old is knackered during the day because he wakes up so much. Me and my husband are knackered for the same reason. What the hell can I do to sort this out?? Please genuinely any HELP welcome. If you have nothing nice to say please move on past as I'm an extremely tired, feeling sh*tty mum that's asking for advice.
Side note, the house is not haunted, I've lived here 36 years. It's a very loving home, the kids are well looked after and my husband helps out equally.

Sounds really tough..
Have your boys always been like this or has it recently started.. and did it come on at the same time? Any triggers?

For 10 yo- go with it atm, hopefully you being there will make him feel safe, once the fear settles, start to gradually move away e.g. pretend you've forgotten something and leave the room for 30 secs, just make sure you always return, then say you'll stay by the door, then by door with door open.. go at a steady pace rather than rush him. We did this ith my 6 yo and he now goes upstairs to toilet on his own.

For 8 yo - I'm less sure what may help.. maybe try mixing up his routine.. you're all expecting him to react like he does and he's ready for it too. Could you do a late night trip to the shop or walk to look at the stars. Then do your routine differently just see if it lessens it at all. I was told once that if you go to bed with the intention to sleep you won't sleep but if you go to bed because you're tired then you will. I'm wondering if this applies to your 8 yo in some way?

Hope there's something helpful in that - I'm waffling a bit now!