Roll with it. Most of us have given people reason to mistrust. Just keep doing what you're doing and hopefully your behaviour will tell in the long run.
It's hard to suck up things like this but I always reminded myself of the times when I was accused, I lied and I got away with it. Maybe it's payback
P.S I eventually lost a job after I was accused of relapsing when I was 9 months sober. There were other reasons, but that was the root of it. Hurt like hell. I eventually got a better job.
P