((((noles)))) I am so sorry for your loss. All good advice above, so I won't add to that.
I hope that you can let go of all the things you "coulda, shoulda, woulda....", because it sounds like she loved you kids with all her heart. I am a mom of a daughter about your age, and us moms love our kids so very much! Your mom loved you too, even though she had an addiction problem with alcohol. Her choices were HER choices when it came to alcohol likely caused by her inner issues. None of this is your fault!
I have lost loved ones close to me. It hurts. I hope that by sharing here and remembering the good times and that she loved you so much will help you through the hard parts of your loss.
Sending you a BIG hug...