Just yesterday in my job, we were talking about whether or not we were 'mandatory reporters' (people that are required by law to report harm, neglect, etc). And while technically we are not, someone said "but we're still ethical human beings", so of course we would 'report' abuse, neglect, suicidal ideation, homocidal ideation (etc).
Personally, I would make only one phone call, and that would be to CPS. Those kids come first, they're innocent victims without a true voice. This needs to be on record, especially if it ever comes down to a custody transfer to the father, or what have you.
To know how they're being treated (and mistreated) and not doing something about it, is unethical in my opinion.
But again, that's just my opinion, I don't envy your position. I don't keep toxic, addicted, or mean people in my life. Period.