Thanks for all the advice. I don't have fear of actual physical violence to us. However if we shared custody I am afraid he would:
1) pass out drunk and leave the kids unattended (he's done this many times while I was home, kids are 3 and 5 now)
and/or
2) drive them places under the influence, especially if he lives alone without anyone to monitor his alcohol intake.

I will certainly look for lawyers familiar with this type of situation as well as counseling for me. Thanks again.