Talk to a couple lawyers and find out about divorce issues. That will give you the information to make the best choices.
It's easier to raise children alone than with an alcoholic; everyone is happier. My sons were 3, 6 and 7 when I left their alkie dad. We lived happily without him, until I foisted an alkie stepfather on them. Left him, and they are fine. They are now 16, 18 and 20 and doing very well (the oldest had a few problems because of alkie stepfather, but those went away with alkie stepfather).
Do you have financial resources if you divorce? A job, a savings account, or does he have a job that will support you and the kids while you are getting on your feet?
Good luck to you, do your research and have more confidence in your ability to cope with the changes.