Fear is a perfectly rational response to danger. Fear can keep us safe. But a state of perpetual fear is not sustainable and it is not healthy.
Everyone has an HIV status; you are either HIV-negative or HIV-positive. Taking an HIV test won't change your status but it will let you know what it is. Not taking a test doesn't mean that you are HIV-negative; it simply means that you don't know your status.
HIV-undetectable is a term used to describe someone who is living with HIV but on successful and effective treatment.