Hey man, I'm sorry I don't have much advice, but trust me you'll find a way out of this. And it's not your fault for not being able to do anything about it.
If you can, try to switch to a remote job somehow. At least there won't be any commute, and you'll have some energy to spare at the end of the day, which you can use to grind and work on some projects. 15k is extremely low, but the silver lining is that even if a remote-friendly company underpays you, it probably won't get any worse than that. So at least financially you'll be at around the same level, if not slightly better, and with the benefit of being significantly less tired without the commute.