How do you get the "bad taste" of an argument out of your mouth?

I ‘acquired’ a friend a couple of years ago, due to her being a neighbor. Years ago, I knew she existed but had mentally marked her as a no go area, since she is very volatile and loud.

However, years passed and we became ‘friends’ of sorts. For a while now she has been pushing my buttons. If I buy something I am asked how much it cost. In fact everything I do I get asked how much it cost. Or, how much I earned this month, how much my flat sold for, the list is endless. I had backed away further and further. Once my toilet made gurgling noises and she got the key from the supervisor to come in and scream at me at 4am in the morning to pull the ball cock up! as she thought it was a leak. We live in an apartment building. Each home is private!

Today I reached breaking point. Yes, I admit, name calling, back and forth, swearing you name it. It was horrible. I don’t want her in my life. I never really did. I need her to be gone!! But I have a vile feeling about it. I hate when I lose my temper. How can I let this go without feeling like crap!