My parent won't stop spending

My family has recently been experiencing financial trouble and my parent just won't stop spending. I (19) live with my parent (45), older sibling (20), and 2 small dogs. We own our home and were relatively financially stable until recently. With my parent on medical leave due to mental health issues and workplace violence, we have been struggling to get by. My parent gets reduced pay through the state, but that is coming to an end soon. My sibling and I are working 3 jobs between the 2 of us, while paying our way through college/university. As a household, we fall into a very unfortunate grey area where we make too much to qualify for assistance and too little to be able to afford schooling and basic living expenses.

The issue is that when my parent isn't attending treatment, they are shopping. I don't mean extravagant luxury spending, but frequent and frivolous buying. Shopping for vintage clothes and items has been their special interest for a very long time, but they've always done it in moderation, and only when everything is squared away. Since their reduction in employment, they go nearly everyday and buys things. Sometimes it is really nice finds, maybe a name brand jacket or some jewelry here and there, but other times it is trashy fast fashion or junk that they aren't even sure they'll wear or use.

While they aren't dropping hundreds each day, they are spending 30-60 dollars a day at least 8 times a month. While that doesn't sound like a lot, it has come to the point where I have to choose between paying for my upcoming semester or the mortgage with my savings come next month. My sibling's tuition is far lower, but they also have a car payment and is helping with groceries and bills. My parent shops, doesn't wear/use it, and then gives it away a few months later. They buy art supplies and stickers that never see the light of day.

I have been their "reasoning center" for the last 10 years or so of my life, keeping them from going off the walls when things get tough, but I don't think I can do it anymore. Not only do they shut me down when I try to explain to them how their spending is stressing me out and breaking the budget, but they lie to me and my sibling about stopping. They'll say "I'm not gonna buy any more clothes" after we talk, and then the next day I'll come home from work and find 3 bags stuffed full of clothes, just for them to say "Oh, I got everything half off."

I get it, my sibling and I are technically adults and know that we could be self sufficient by this point, but our entire lives we have been told that we can stay until we have enough to buy or rent reasonable accommodations. My parent has always stressed that they wish for us to finish school and find good jobs before we seriously consider moving out, but that was when we as a household had them for (at least partial) support as a financial safety net. Now, with their employment future uncertain, and my sibling and I having increasing expenses as we move into fully fledged adulthood, and I'm scared.

I have done the math, and realistically I could move out/support myself if I were to get another job, give away our dogs (I really, really can't handle this), and drop out, but I don't think I can do it. I know people younger and in worse situations have done it, but I don't think I can. I mean, we went from being homeless for a year when I was 10, to being able to buy a home just as I turned 15, so dare I say I have been spoiled and gotten comfortable with stability. My childhood in a multigenerational, single-parent home has made me an extremely money focused person, and I take my and my family's finances very seriously. We utilize food banks, couponing, and RARELY (if at all) eat outside food, but we are human.

I just don't know what to do anymore. I can't afford school, our mortgage is increasing, and my parent just won't stop. I feel like I've betrayed myself and my family, but especially my parent because I no longer trust them to support me or be a voice of reason. They say that they're being encouraged in treatment to treat themselves with kindness after the incident that has them out of work, but I feel that their choice of "kindness" is going to destroy them and their independent future. I know I will weather this chapter in my life as I have before, but I don't know how to support myself, my sibling, my dogs, and my parent without falling apart.