I am going to go ahead and let my staff know that my roommate/friend cut herself.
For what reason would you share that with your staff?
I just think someone should know, and I am bored as well.
I'm glad you're concerned for your friend, but telling your staff at work is inappropriate and violates the trust of your friend. You should be supportive of what your friend is going through and try to encourage them to get professional help, as what they're dealing with is serious and very dangerous.
She is okay with it, I told her it's fine.
With all due respect, your friend isn't in the right headspace to be making a judgement call on you sharing this personal information with your staff. It's simply very wrong for you to do and I hope you reconsider and refrain. Focus your energy on getting your friend the help they need.