Mercedes,
I'm so sorry that you are going through this.
As others have said, I understand that you want to look for an explanation. The sad truth is that we alcoholics can't explain the insanity any more than you can. We have a problem that defies explanation.
What I can tell you is that it's not about you. You're not at fault in any way; there is nothing you could have done to prevent this. It's a selfish and awful thing, addiction.
If you didn't like the Al-Anon meeting(s) you attended, try others. Each meeting is unique and I think/hope you can find one that fits if only you look hard enough.
O