Just filed for Divorce and custody, how to deal with...

My ex is a narcissist, mental and emotional abuser to me and alittle of our children. Hes Just getting out of a 8 month rehab. He has 20 yrs of drug and alcohol abuse. And even has physically abuse reports from his ex wife. Im About to go to custody battle with him. He has drank and drove with our children and left them in the car and many other issues happened too. How do you get past the fact that you may get 50/50 custody? Any chance to get full with just visitation?

Anyone go through this? Any tips to stay less stressed not worry or anything to add to help me in general?