Thank you for writing. I did not see your correspondence until just now, so please forgive me for making you wait.
I understand your predicament. I would suggest that on your way to class, and as you are arranging the space and getting the lighting just right etc, in the back of your mind talk to God (quick words). Ask inwardly for guidance about what to do and what to say. If you have a favorite Awakened One or favorite teacher, ask them to speak through you as you teach. Then relax and breathe and just be normal 🙂 Say “Good morning, bonjour.” Thank them for coming to class. I would probably omit the injuries discussion, do that in private. And then begin. To me, it sounds like you are doing everything just right. You just have to be more at peace about your approach, clear within yourself that you know a good pathway into the practice, and then in a friendly way, say, “Let’s start.” It usually takes me a few minutes to get ready, people are coming in, and then I say, “Are you ready?” and we begin. I have been talking/preaching the first 10-20 minutes of class, but I used to just start with seated meditation. Lying on the back is excellent, too.
I realize I am not saying anything dramatic. Mostly, I suggest, just be clear within yourself that how you are doing it is a good way, and don’t let yourself be swayed by their “life sucks” faces.
If people are in your class, and they keep coming back, you are definitely doing something right.
Your English is excellent!
Love and pranams,