What do you want to do? There are quite a few things you can do in history. The traditional route is to become a history professor, but the job market is abysmal in that field and it would require a PhD that takes on average 8-10 years to complete.
You could become a history teacher, which would likely require a master's (or second bachelor's) in the field combined with teacher certification. That would probably take you 2-3 years to complete.
Or you could do museum work. There are a variety of degrees that lead to a variety of jobs within museums. Museum curators usually need an MA or PhD in history, but there are a lot of jobs in museums that only require bachelor's degrees. You could also be a public historian, which may require an MA or a PhD in history.
The thing is, there's a difference between being passionate about a field and wanting to study more of it and having to make a career out of it. I too love history, and I always joke to people that if I hadn't gone into psychology myself I might've gone into history instead. But in reality, I don't think I would. The study of history as a scholarly pursuit is different from the casual interest (even casual passionate interest in it) as a hobby. I read historical novels and histories all the time and I am able to indulge in my interest - even a very specific time period interest that could be developed into a research topic - without necessarily getting a degree and working in it. You could do that too, if you wanted. I guess what I'm saying is that you have to determine whether a career in history is worth the sacrifice for you, and worth braving the very bad job market in that field to take a chance, especially when you will most likely have to pay for your degree unless you get a PhD.