Take care of yourself first

Unconsciously, you are trying to find your self-worth through your children (their wellbeing, etc.)  You become dependent on them, and they hold the lever to your happiness.

Love youself first.  You don't need to prove to anyone your worthiness.  You are good enough.  Don't let anyone tell you otherwise.  If they do, find out what is hiding behine that assertion.

Educate yourself about personality disorders.  You may attract these types of adults.  Your daughter is still a minor.  But you will learn how to handle this types of people.  Do it before they ruin your sanity.

Again, maintain a healthy sense of self, by being willing to shoulder yourself.