Posting from phone so brief, felt compelled tosay: Not your fault ever that she drinks. Alcoholics drink for every reason: sad, happy, stressed, disappointed, celebrating, etc. etc. etc.
She probably wants to be alone so she can drink without interference. Alcohol is her 'OP'.
Great that you are going to Al-Anon!
M 16 yrs, WH62, P54 3 adult blended kids EA 11/13, BD1 6/14 PA fall 14, BD2 2/15 Piecing 2015, BD3 12/15 Separated 4/16 WH moved OW in 5/16 Divorced 6/15/17