Where to start


I am working on getting my citizenship, and I am not sure what laws I need to take in consideration when thinking about legal separation or divorce.
I am married now 8 yrs to a US citizen, but there are lot of problems I just can’t deal with any more (alienation of affection, unemployment, “mental health” problems, anger management, etc…)
In the 8 yrs I received my green card, but no word on when I am eligible to apply for citizenship and my passport is expiring soon, too.
We have no children together so my case should not be that complicated.
I am a little scared to file for divorce because of his reaction, but this is an unhealthy place for both of us.
I don’t even know where to start.
What is your advice?