My friend saw my messages bitching about her?

[Swifty]

Today my friends, J, Z and I were studying in the library. J asks to borrow my notes for our upcoming term exams because she told me she didn't copy anything during lectures. I am really annoyed by this because she NEVER pays attention in class (either sleeping/using her phone/doodling etc.) and before tests/exams, she will freak out and then ask to borrow notes that other people painstakingly made. I can't tell her no because she'll get mad and I don't want her to feel like her friends refuse to help her when she needs it, but I don't want to just lend her so simply. So I whatsapped Z (who's opposite the table) to complain, and being quite the potty mouth, the content went something like (censored for posting purposes):
"Seriously? Again? I don't f*ing wanna lend her! he's slacks for a whole term and expects people to help? F* her."

Z replied me and I didn't check, then J (who always uses my phone) reads it before me. x_x She never lets anyone use her phone but she always reads my messages and posts things on my Twitter without permission. I see her at it too late and snatches it back, but she has a really pissed look and informed me on the way home that "Sorry I read your messages, but I'm still gonna borrow your notes tomorrow."

Um okay but I don't wanna lend her anymore..? And how do I smooth this over when I don't feel like apologising for something I really feel? Sometimes my other friends and I get the feeling that she thinks she's doing us a favour by bequeathing us with her friendship as she's supposedly more popular, and during lunch she will ask us to carry her food and clear her dishes for her (sometimes).

The thing is I tend to drop cuss words very frequently especially over text, and it sounded extra bad when she reads it. Any idea what I can do now? It'll be so awkward tomorrow LOL
Thanks guys My sister told me I should just go kill myself but I feel a little better now. It somehow doubles the bitch factor since we were all sitting at the same table but gahh it was THAT annoying for me to complain right there. Actually J is okay to be with for most of the day but at times (e.g. when she just stands up after lunch with no intention of removing her plate (so we stack it onto ours)) or when this happens it can be very irritating.