Embarring or not?

Yes. It is embarring for a teenage boy to be in that situation but put it in your past. Your Mother did not do any of those things on purpose so let it go. She was embarred also because she laughed while apologizing to you. A laugh can be an expression of embarrment. I'm sure you would not have shared a bed if another bed was available so don't blame her or yourself. It is over so let it go.