Respect yourself enough to walk away from anything that no longer serves you, grows you, or makes you happy. If you aren't being treated with love and respect, check your price tag. Maybe you've marked yourself down. It's you who tells people what your worth is. Get off of the clearance rack and get behind the glass where they keep the valuables.
A man can stand a lot as long as he can stand himself. ~Axel Munthe
Don't let someone who did you wrong make you think there's something wrong with you. Don't devalue yourself because they didn't value you.
Letting go of people out of your life doesn't mean you hate them, it simply means you respect yourself. Not everyone you meet is meant to stay.