Paige,
If you want sole custody or supervised visitation you have to start keeping records now, keep a journal, how much he drinks, any incidents, date/time/event, how long is he away on these binges, does he miss work, can he manage money, take care of his own hygeine etc, does he do anything to take care of the the kids, is he capable?
If you use the computer get a thumb drive and hide a copy on it.
I prefer a good old fashioned marble cover composition book with the sewn pages, when I dealt with a work lawsuit a few years ago my lawyer told me the courts really like these books because they cannot be manipulated like a computer or a loose leaf notebook can, if you do it this way, make copies every so often and get them somewhere safe (your moms or a sfe deposit box in your name omly) also, I would recommend one of thos cheap little digital video recorders that uses the memory cards, you can set it on a shelf and leave it run and capture bad behavior.
Best of luck,
Bill