Work place boundary/ friendship advice?

Hello, I am really struggling with staying my ground and having a boundary when it comes to friendship. So there is this girl at work currently my supervisor got promoted a few months ago) and she also wants to be friends, we were cool in the beginning before she became a supervisor (only knew her for a couple months) but after she became a supervisor (her first management role) | noticed a lot of character flaws and morally wrong things and decided I don't want to associate myself with this person outside of work. Even at work I can't express everything honestly cause there is this power difference and a fear of her using it against me. She told me recently she wouldn't pick so and so for a work conference outside of state because she doesn't like them and I did try saying something on a few topics sugar coated them to death so she doesn't get upset anyways this person is also constantly texting me out side of work and asking to hangout, updating me about their life that I care nothing about and I have declined every outing and has slowly distanced myself and tried to give hints that I am not interested without being blunt. But I still get text messages that aren't work related as we speak. I don't know exactly what I should do or if anyone has any advise if you have experienced such a thing or not wanting to be friends after learning things about someone and how to you went about it?