I am sorry that you are going through this. This site has a friends and family section that you can get a lot of support from. While it may be hard to attend an meeting, it would definitely be worth it. You could also try an ACOA meeting if you grew up with a parent with an alcoholic or addict. Not sure if it applies to you but the tendency to want to rescue and help people, confuse love with pity and get in relationships with people with addictions are classic ACOA traits. I would highly recommend counseling if that is an option.
Know that you are making the right choice- you and your children deserve better. My ex-husband delved into crack shortly after we were married, and it was the fastest downward spiral that I have ever seen. (and this is coming from a hardcore alcoholic!) I also had to make the choice to love myself more than him by leaving. Your enabling also is what helps him maintain his addiction, and losing your support and sinking to a new low may be what he needs to finally get better. But don't ruin yours or your kids lives by waiting around and hoping. While scary, you are making the right choice
Best of luck to you, and keep posting!