Oh, that's a tough one. Sounds like you're in a harsh situation, sorry about that.
I think it's not that you're unmotivated - or this problem wouldn't be on your mind 24/7 stressing you out. You're just overwhelmed.
There are many different ways of dealing with stress. Sometimes I feel better after breaking stuff and listening to "angry" loud music, sometimes it's the opposite and soothing stuff such as laying under a heavy blanket, taking a shower or watching mindless relaxing videos helps - it depends. I also find grounding techniques helpful when I feel anxious or overwhelmed.
Are there any way for you to make the process of studying more pleasant without being distracted, such as putting up your favourite music, making a hot drink of your choice etc.? Also, when I'm facing a big overwhelming task that I dread, I try to break it into smaller, more accomplishable tasks, and take breaks in between, doing something I enjoy. Do you think this can work for you? Can you think of stuff you can do during breaks that will make it feel less stressful?