You want to be sober and acknowledge that your life is unmanagable, good 1st step.
It is not a matter of getting sober before your teenager's lives are negatively affected, because they have been coping with your addiction and unavailablity for their whole lives.
To get sober, you have to put recovery above everything else.
Find someone to take your kids and go inpatient. Go to an AA mtg. tonight.
Let your ex, or your siblings or your parents know that you need help.
Do it for your kids. You only have a few yrs. left before they are adults.
Get healthy and give your kids a mom who can nurture and love them.