No 18 year old wants or appreciates her mother micromanaging her down to if she wears a hoodie in the house, or not. I think you set her off with that.
Now, that doesn’t excuse the foul language. In my house, I allowed foul language if the situation warranted it (slamming a finger in the car door, breaking an expnsive piece of furniture through carelessnes, etc). Being triggered because mom made an unreasonable request wouldn’t have risen to that level, so I would not accept the pottie mouth in the situation you described.
18 year olds know they are legal adults, and they want the respect that might suggest. I would suggest being careful on advice you give and requests you make. Of course, to us older folks, 18 is still a baby. It is difficult, no doubt.
Bottom line, I would tell her if she wants to live with you, she needs to clean up her act. Spell it out for her, as far as what your expectations are. Nothing wrong with asking her to move on if she can’t abide by your house rules.
It is about basic respect, in both directions. If you let it slide now, it is going to probably get worse. Show respect, and expect respect. Both of you.