I’m trying to understand Git, but it’s a giant conceptual leap.

In that case, I suggest learning Mercurial first. Its underlying design is very similar to Git, but the interface is more consistent and does a much better job of presenting the concepts to humans (especially those already familiar with traditional version control). Then, once you're comfortable with the concepts and commands in Mercurial, learn Git, since it's everywhere nowadays.

Consider learning at least one new language, if not immediately (since you're in a hurry) then in your free time. Java is only one of many (and not even a particularly nice one IMHO). Try to find a language that you enjoy using; your programming life will be better for it. If you want something flexible and productive, consider Python. For more structure than that, maybe Go. If mobile apps interest you, there are Kotlin (Android), Swift (iOS), and Dart (both). If web development appeals to you, along with lots of job openings and lots of competition for those jobs, JavaScript. If you fancy the esoteric (and well-paying), Elixir and Erlang are worth a look. Lower level languages are in demand as well (e.g. C++, Rust) but they come with various kinds of pain that I wouldn't recommend to someone in your situation.

Above all, please make sure you're reserving time for things that make you happy, sleep, and (if still possible) some kind of exercise. Your own physical and mental health are important. If you endure a bad working environment or wear yourself thin for too long, you will burn out, which won't help you provide for yourself or anyone else.

Take care, OP.