How do I kindly but clearly tell my clingy, needy flatmate that I don’t want to have dinner with her every night nor I want a family substitute?

I moved in a new flat two weeks ago with a 30 years old woman I didn’t know. She expects me to eat with her every night and is visibly upset when I tell her I made other plans. She has friends, but expects me to become part of her friends group, on Saturday she asked me to go on a walk with her and her friends, I told her I had to do the groceries etc and didn’t have time, and she got upset. I would like to explain to her that we are two people who don’t know each other and not a family and that I have an independent life. How do I do that kindly?
How do I kindly but clearly tell my clingy, needy flatmate that I don’t want to have dinner with her every night nor I want a family substitute?
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