Oh dear SG, your post made me want to hug you very very tightly (even better if you are wearing babySG in a sling, then he'd get a cuddle too).
I don't really know what to say about the feeding, it sounds awful, I don't know much about bfeeding but it really could be trush. All I can say for the time being, try to relax about the expressing, seriously. there's every chance baby will latch on again, and if not, you'll cross that bridge when you come to the water, for the moment you are getting some relief, and that's the most important thing, honestly. It is a bit alienating, but remember it's still your milk, for your baby
A couple of practical suggestions- what pump are you using? you can rent some "industrial" ones from NCT or the hospital whcih are very efficient and will prob cut down on the expressing time quite a bit.
re comfort sucking- what about a dummy? I know you are prob worried about nipple confusion, but tbh I am very dubious about that with dummies, I have seen dozens of bf babies with dummies, and if your baby takes to it, it can be a real life-saviour. My dds never wanted them
Colic IS a nightmare, I have been through that, sling is the only thing that will help you preserve a shred of sanity, unfortunately it's just one of those things... you've got to ride it out. it seems like it's never going to end... but it will. I promise!
also (reading between the lines) don't feel guilty about your DH being shattered. It's par for the course, you are new parents, being shattered is completely normal, trust me in a few months you'll be able to smile about these days.
I know none of this is remotely helpful... having been in a similar situation (minus bf woes...) i really felt like i was in a tunnel, in complete darkness, and i didn't believe anyone who told me it would get better. Most importantly, it didn't matter to me, because the here and there was too hard BUT, it did get better, in fact it got wonderful, and that really hard bit was incredibly fleeting.
Try to sneak in lots of skin on skin with your baby, even if not bfing... perhaps take a bath together?