Very much this. You can't make it perfect, but there's no plot hole that you can't at least partially fill with something. Also don't forget that you're your worst critic; what looks massive and breaks the story in half might just be a weird inconsistency your readers just shrug and don't pay attention to. It's best to come back to it with a clear mind instead on focusing on how the task seems impossible.
There are no such thing as an unfixable plot hole in fiction. You just didn't figure out yet what you could do and I bet there are more than one solution. If you need help explain me your problem and I gladly will point you to a direction.
Many, many creators on this site would help you through this... would see it as a challenge. 
Don't give up unless a better idea comes along.
I dunno. I just feel like this is the biggest bruh moment in my history of writing. Like, how did I not see this? It's so obvious. I'm more than ten thousand words deep into this plot hole with nothing I can do to salvage it.
As others already said, it's very likely fixable.
I'll go even further and say a well fixed plothole can potentially be an enhancement, as the fix can add depth to the story, or constitute a great plot twist, etc.
The issue is that if the plothole is really huge, fixing it properly may considerably alter the continuation of your story, but you're saying you like to write as you go, so it should not be a large issue.
Is the plothole already apparent and problematic in what's already written, or is it only that you realized that you won't be able to have some things make sense further down the road?
I don't want to discount your self-flagellation or anything, but...I mean, if you managed to ignore its existence for so long that you're 10K words into it, it might actually not be that noticeable to people who aren't you. ^^; You might not even have to fix it completely; just a partial patch that leaves a few things to the imagination could functionally save the story.
And if nothing else, you could always just ask other people how they would go about handling it. Even if there's no way to salvage all 10,000 words, someone might have an idea that will only require you to rewrite 5,000 of them, rather than scrapping the whole draft.
I agree with what some other people are saying on here! A lot of very famous and beloved stories have plot holes and story choices that the audience is willing to roll with, even if they're a little nonsensical. We can all forgive Lord of the Rings for the eagles thing (not really a plot hole so much as a 'why the heck doesn't Gandalf just summon the eagles to take Frodo to mt. Doom?' but you get my point). I actually think plot holes are relatively simple things to cover up, too, if you're clever about it. I'm sure my story has some plot holes and inconsistencies that I'm going to go back and fill in once I finish part two of the story, but for now, I kind of just want to focus on writing the darned thing.
I think you should only give up on the story if you've really and truly lost passion for it and you simply don't like it anymore. Otherwise, keep on trucking!
Thank you to everyone who has given me advice and encouragement. I think I'm just being a big, uncreative baby about this whole situation. Accumulation of sleep deprivation and work stress is probably just making the storytelling part of my brain short circuit. I'll just cheese a fix and hope I-or anybody else-doesn't notice any other glaring issues with the plot that arise from the cheddar, swiss, and brie.
I think in my panic my creativity got Thanos snapped. I was able to temporarily push the problem further down the road for future me to deal with.
I wrote 17,358 words of a book before I realized it wasn't going to work. Scrapped it all. Two years later I tried again, plotted every scene of my book from start to finish, and I wrote the entirety of the manuscript in just under three months, no plot holes. 86,234 words.
In the grand scheme of things, 10K is discouraging but not a death sentence. Maggie Stiefvater deletes about the length of a whole book from her whole book before she reaches a final draft. Re-writing is just as much part of the process! Casualties happen, and Rome wasn't built in a day. You can do it!
I recommend taking some time to reevaluate, find someone to discuss the in-depth aspects of your plot, and eventually, you'll figure out how to patch up that hole. Good luck, my dude, I believe in you.
One thing that I learned can help if you are someone who writes without a main direction of where it’s going to go, is to CONSTANTLY reread your work as you write. Doing this has helped me uncover so many plot holes or mistakes I was about to make. It also is a good way to tie in things you’d already written to future chapters you’d like to.
Are you 100% sure there’s no work around to your plothole? I’ve had to come up with extra ideas to have things make sense so a plothole wouldn’t form in my work.
I think this may also be a sign you need to stop being a person who writes without knowing where you're going.
I know it's not possible for everyone, but as somebody who used to think writing by the seats of my pants was my only option, I've learned outlining is a pain, but a lifesaver. It's a skill to be learned, not always a natural inclination. I find it helps to focus not just on events but on character arcs and themes.
Most people who write as they go function by going back and making tons of changes to make something satisfying. That means most people either have to learn to plan ahead, or get prepared to do some radical surgeries to make their stories work.
I'm also an outliner-to-the-max, but I've argued about this so long (blue in the face) I eventually figured out that for some novelists the possibilities stage is the most fun part of writing, and they'll never ever give that up or shorten it, even if it means 8 extra lengthy rewrites.
You're Spocking someone's Kirk. 🤷♀️
I know it's not for everyone.
I am just an ex-NeverOutliner and I think people often think if it doesn't come to them naturally, it's not for them. It's often seen as a natural preference rather than a thing you can choose to build.
I definitely don't want to imply OP has to do it or 'it's your own dang fault for not doing it', just that it sounds like not planning ahead is giving them a lot of heartache and I wanted them to know 'being a person who doesn't outline' is not a fixed trait.
tldr; Metaphorically, I am a Kirk, but I've learned I save a lot of heartache if I listen to my science officer a bit more often
I'm sure you can use that to learn and also as a base for another novel! If the story was well-written to begin with, I'm sure you can reuse some stuff you've already written and work around that. Good luck!
No plot hole is unfixable. As has been said in this thread already readers will forgive, or look past entirely, a plot hole if the book is enjoyable.
I had a massive oversight in the novel I completed earlier this year. It wasn't quite novel-ending, but it was glaring mistake. Took the time to fix it and the story came out better for it with the changes I had to make.
