Remind him irregardless of whatever happens with your mother he has more than her depending on him, hell just remind him you love him. Needless to say I have never been in your exact situation my dad was an alchoholic growing up and my mom a nervous reck, I was hospitalised for depression for a few months these experiances taught me you cannot leave things to fester it's essential you confront them and say everything or it will always haunt you somewhere.
It's tough and things wont be easy but it's worth the gamble things wil improve one way or another.
It's tough and things wont be easy but it's worth the gamble things wil improve one way or another.