Dear Amy: I believe my best friend "Lara" is knowingly the "other woman" in an affair.

Lara has recently started seeing "Jonas," an ex from her college days. He contacted her about six months ago, and it began as a friendly conversation from afar (they live in different states). They've seen each other in person twice — once at a hotel when she was traveling for work, and very recently when he visited her at her home.

Before their recent meet-up, I expressed my concerns because the last she knew, he was still with his longtime partner (with whom he shares two kids). Lara said that Jonas and his partner are together in name only, and he plans to end it.

I fear that Lara has blinders on. Many easy-to-find clues on the internet have led me to believe he is still very much with his partner.

I am not comfortable hearing about her relationship with Jonas. I wonder if I should have another talk with her — or even contact Jonas' partner.

Amy says: I agree with you that your best friend is most likely knowingly the other woman in an affair.

She has access to all of the information you have access to — and more. And so, you have no duty to tell her, and you certainly have no business notifying Jonas' partner, who is a total stranger. In short, none of this is any of your business. You're completely off the hook.

You obviously don't approve of this, and you may be worried about your friend getting hurt in a situation that is almost guaranteed to hurt at least one of the involved parties. These are things you have the right to express, using "I statements," as in: "I don't approve of what you are doing. I'm very worried that you are going to get hurt."

But that's it. Your friend has the right to live her life the way she wants to live it. Her choices may harm her, and may harm her relationship with you. Those are the consequences of her choices. She — and you — will have to accept them.

Invasion of privacy

Dear Amy: I'm in my mid-20s and have been living with my folks, post-college, while I save money to move out on my own. I sleep (and mostly live) in my childhood bedroom. I work in a restaurant, so I eat most of my meals out. I pay $350 a month to rent my room.

I bring home a fair amount of cash from tips. Because of that, and honestly because I suspected my mom was going through and occasionally borrowing my things, I installed a camera that is connected to my phone.

Long story short — I saw my mother enter my room and engage in what I would call basic snooping: Reading stuff that was on my desk, looking at bills, looking in my closet.

I was creeped-out but not surprised. I asked her about it the next day, and she was highly offended that I had installed the camera. She insisted that I remove it because it is "her house."

I'm frustrated and would like your take on this.

Amy says: It might be your mother's house, but you are renting a room from her, and this should be your private space because you are paying for it. (And she should respect your privacy, regardless.) I think it might be time to get a lock on your door.

Understand that this whole episode very likely could lead her to ask you to move out.

Send questions to Amy Dickinson at askamy@amydickinson.com.