Honestly, darling, the problem is not that your T talks about her daughter. The problem is you feel envious and jealous and unloved and probably unlovable. Getting your T to never mention she's the mother of a loved daughter won't address the real issue of your emotions.
You suffer from jealousy and envy, you feel unloved and unlovable, you know it, you've identified it well and what triggers it. That's good. You're miles ahead of most people who suffer from envy and jealousy.
Now, please consider telling your T you want to work on yourself, on your own emotional reactions, not that you want to make her change so you don't have to think about it.
I wish you well in the New Year and hope this will be the year when you begin to know in your soul that you're amazing in your own right.