There are also a lot of jobs that are tangential to pharmacy dispensing - I work in one of them as a software analyst.
It's nice because my customers and I both benefit from my knowledge - because I can speak their language, I am able to be a lot of help to them. There's also consulting and insurance and all kinds of other work for which you are eminently qualified if you want to stay in the field.
On the other hand, I have a friend who was busted for his illicit drug use and returned after a time to his job as a dispensing pharmacist. He was scheduled for weekly drug tests for a good long time, and is still called in for random tests. I don't know how reassuring that would be for you, but I do know it was a great safety net for my friend.
Your former boss sounds like an awesome human being. I don't think he would be offended at all if you just told him the straight up truth.
O