Your last line is so sad.

I think we need to tell parents they matter. That their love and their values set the stage for their children's willingness or unwillingness to open up and trust that their parents love them no matter what. That their parents care and and forever their parents will love them and respect them, even if the choices are not what the parents would want for them. 

This is a good read, esp. this section: "So, what do we need to do to foster an open relationship with our children?"
http://peacefulparentsconfidentkids.com/2015/02/teenagers-dont-talk-to-their-parents/

Years ago my mom told me that it was not critical that one parent be home with the children when they were young. But it was imperative that one parent be home when the children were home, once they reached high school. She said that teens are faced with choices that they are ill-equipped to handle maturely but ones they can act on impulsively! And that those are the decisions that can go bad fast.