In your case, because you are using the 5 year rule, it doesn't matter whether you are living apart, living together, or divorced (unless you spent an extended period outside the US while your spouse and children remained in the US, and you want to use their presence in the US as evidence of your ties to the US).
Living apart can trigger request from USCIS to prove that you are financially supporting your wife and children, regardless if you are filing under 3 or 5 year rule.