AITA for quitting because I was scheduled for Boxing Day?

So I work at a jewelry store and while I enjoy the product and the people, I've had a few issues there that have all lead to this moment. This will be quite long as there's a lot of backstory so TLDR at the end.

I'm a university student, and have been in school full time up until this point, and working at this store for the past year and a little bit. I am now going to be taking a couple of semesters off because I have some health issues that need to be dealt with and my body really needs a break... I've definitely been pushing too hard for a while. And a lot of my health issues (the main one being chronic severe ulcers) stem from stress and anxiety, which this job doesn't exactly help with.

At this job, they heavily stress numbers. ADS (average dollar sale), UPT (units per transaction), AUR (average unit retail), conversion (how many people who come in buy) are all looked at for each individual several times a day. It's very high pressure and they set some very unrealistic goals for us every week. At the end of every week your stats are posted and ranked with other employees. Beyond that there are a LOT of other jobs that need to be done and basically if you aren't constantly moving, you aren't doing enough. One of these jobs is visuals and there are a LOT of displays which are constantly being changed. Our store sells charm bracelets (I'm sure you can guess from that where I work) and so a lot of time and effort goes into styling a display. It was noticed fairly early into my time here that I'm very fast and efficient at creating displays and can get one up in about half the time of any other employee without sacrificing the quality of the designs. And so while this job used to be given out equally to all employees, and a lot of it was done by a girl who's a team lead but also the visuals manager... for a long time now, these jobs have been given almost exclusively to me, to the point where I have often been responsible for almost every unit in the store and the girl who's actually getting paid for this job does almost none of it. I am also the one who entirely maps out the entire store for inventory and basically have to make what I call the scrapbook from hell... a book with a picture of and barcode for every item in display, in order, so that they don't have to take anything off display to count for inventory. This is a mind numbing job that takes days and always leaves me as basically a zombie.

Because of this, and the constant pressure they are always putting on us, this job has always caused me a lot of stress and caused some issues with my health... but despite all of that, I've always loved working here. It should also be noted that I make minimum wage, and there is no commission. Just a really poorly thought out incentives program that nobody really benefits from. So I'm getting paid a pittance to do a lot more work than I would be doing at any retail job and its wrecking my health to boot.

Now this summer I got married, and this has been amazing but also difficult at times because just after getting married, my husband started working graveyards... this severely cuts into the time we spend together, even if it's just sleeping together... we've been doing our best but me taking time off school definitely had the added benefit of allowing us more time together... or so we thought. You see up until now, my availability has always been respected because I'm in school. Now however, they've basically told me that my availability is merely a suggestion and they'll schedule me when they want and I have to be there. I had told them for the holidays that I would work Thu-Mon anytime, just not Tue/Wed because those are my husbands days off and we want to make the most of them. I actually feel this is quite generous of me because this means that when my manager shifts me to close on any days DH is working, then I dont see him for 48 hours or sometimes more. I've been dealing with this because it's the holiday season and we get obscenely busy and I want to be of as much help as possible, even though this really does take a toll on our relationship. The plan was to make myself only available until about 6:30 after the holidays so we always got at least an hour or two together every day. Now I feel as though I can't do that because they won't even respect the two days I said I can't work so why would they respect my preferred hours? They know my situation and that for the sake of this stupid store I have actually gone nearly 4 days straight without seeing him, but the dont seem to give a shit.

Now the difficulty comes from the fact that boxing day is a Wednesday. I literally have no problem with the fact that I'm working Christmas Eve, I only care about boxing day because it's one of his only days off and I am genuinely not open to work those days. I told my manager this and she took the shift down and then a couple of hours later put it back up and told me higher ups said she had to because it's a holiday so availability means shit right now.

I told her that I will likely have to look for work elsewhere where my availability will be respected, and that I'm tired of just being a number in this company that cares so little about its employees. What I didnt say is that I think with how hard I work and how little I work for I deserve at least the courtesy of observing the days I'm unable to work. I do way more than the average sales associate in this store and worlds more work than the average retail worker because this crazy company thinks they're some sort of high end store and that we should be grateful to be doing twice the work for minimum freaking wage. Also our previous manager actually hired enough seasonal workers last year that I didn't even have to work Christmas Eve so I'm pretty annoyed that my manager being so picky has put me in this position.

I told her I would stick around until Christmas Eve because the last thing I want to do is leave her in a tight spot, and that we can talk about it when I see her next but at the end of the day, my marriage comes first. She saw the message (through our work app) but hasn't responded.

Am I The Asshole? Am I at least justified in wanting to find other work? They're definitely making me feel like the bad guy here...

TLDR My store refuses to respect my availability (which is quite reasonable, and I'm already making many sacrifices for them) despite the fact that my husband works night shifts and I sometimes go days without seeing him due to them not caring about the availability I've given. Boxing day is one of his days off and I've basically been told they don't care what the situation is, they can do whatever they want because it's a holiday. I've said I'll stay until Christmas Eve for their sake and then I'll be finding other employment.