Welcome...I'm sure as you read the posts here you will realize everything you feel is so "normal" (as if anything is normal when addiction enters your life) Reading the stickies, especially What addicts do will also confirm that his behavior is pretty much the norm with addiction as well.
Whether you stay or go is a choice only you can make, but I would encourage you to try some Alanon or Naranon meetings -(They are for those who have loved ones with addictions). I'd also encourage you to try to protect yourself financially as much as possible. If his disease is progressing, finances will suffer...it sometimes happens very quickly. Keep an eye on any joint accounts, credit cards, etc and see if you can start separating them and having some things in just your name. HUgs; I'm so sorry you are going through this but youhave found a good place filled with caring people.