(((((Big Hug))))
The short answer is yes, he left you for drugs. When the drugs become more important then people that is just how it is. Those of us who are not addicts may never understand, truly I don't get it, so I just make myself accept reality by reading up on addict behavior, applying it to AH and reminding myself he is not unique to addiction. It's painful but when the pain wears off, you may be glad for the clean break. But be aware he may return one day looking for a soft place to land.