I'm going to act irritated with this woman who brings her infant to class.
Why would you be irritated with her?
She is being inconsiderate of others letting her baby come with her.
I know how frustrating that might be when you are trying to learn. You have a right to be upset if people are disturbing class while you're trying to learn. She might have a good reason for doing so, but you should also let her know that it is distracting.
She should be quiet during class. Fuck her.
I don't think you have to be this upset, but you should tell her that she could be bothering the class.