You'll be fine...better to go and not know what to say -than not go. Once you get there you'll open up, things will come out.
My ex didn't know I was this 'involved' in SR either. But that's ok...you need to do what you need to do to remain committed to your sobriety.
There are alot of things that happen when we drink, usually bad...and it will take awhile for that trust to return. Just keep doing what you're doing and stay on course.