I feel like giving up at times, too. It's too hard, Sisyphus has it easy, why am I driving myself crazy when nobody cares?
I felt that lots of times before the separation, feel it less now. The boundaries I'm learning along with the positive effects of all my support systems (meds included) keep me grounded.
You're their dad, their daddy. Kids need their dad. Ready articles about what happens to children who only have 'visitor' dads or fathers they don't have access to. It's heartbreaking. Your role, your love is a vital part of their upbringing.
