Welcome to the family!
Thank you for taking the time to introduce yourself to the rest of the family! Pull out the keyboard and post as much as needed. We are here to support you!
I have a few ex husbands and a few children. This is what has worked for me. I do not force my ex to be a parent. If they want to see the children, they can make plans. My trying to force them to keep up visitation is me still trying to control someone else's life. It just leaves everyone frustrated and disappointed.
There may be periods of weeks/months that go by without contact from an active alcoholic. Teach your children about addiction, as appropriate, and be sure they understand that they are not to blame! They did not cause it, they can not control it, and they won't be able to cure it.
In the meantime, keep working on yourself. Going to meetings, counseling, self-improvement books, etc. whatever it takes to be the sane, dependable, loveable parent your boys need.