My best friend moved in with me after a nasty break up. At the time my extra room which is in the basement of my house was occupied so she shared my room and my master bedroom. The basement room as become available but she does not want to move there and she does not want to share the other bathroom in the house because my kids use it. I am frustrated and want her to leave but I also do not to damage our friendship, she has been a good friend to me. I just want to have my room and bathroom to myself.

A friend who is your tenant (Assuming they pay rent) who refuses to abide by your rules is no friend to begin with, are they? You have every right to firmly give them their options for continuing to stay with you, and if the friendship cannot survive these changes and adjustments to your living arrangements then that would be their choice.

You must allow them to make that choice friend or not and accept what comes of it if truly they are a friend. Mixing friendships and business is always a difficult balance but if you want your space back, then you do what you have to do.

Do they indeed pay rent and share the household responsibilities? Give them a written notice of your changes if they refuse to cooperate. Otherwise they have effectively taken over your home and that's not very friendly either.

You may need to just mover her stuff down to the basement room on your own, explaining to her you really need your privacy back.