Welcome back to SR.
A relationship is not worth suffering physical abuse. NO ONE should be punching you in the face or anywhere. NO ONE Should be attempting to drown you.
I am sorry for your hurt and for all that you have been going through.
You can be the father you want to be and the father that your children deserve. Start today with a new sober approach to your life and dont look back. You are worthy of so much more. You just have to know it and put your health and your children first.
Log on here and post. Go to AA if that is what you need. Make a plan and work the plan. As PJ said, no contact and if you have to file a restraining order get on it now.
With each passing day and the decisions that you make, life can be healthy and beautiful.