My neighbor cheated with his partner's sister, and now lives with the sister. The most aggravating part of it is that he has kids with both. Every other week his ex has to come by to drop off her kids at her sister's house since they share custody. From the kids perspective, their sibling is also their cousin.

Her ex's new girlfriend.

Your partners child.

Magic Johnson

The one that we made a sexy time video years ago that I have since forgotten that it was still in on my computer, that she found and it caused a big argument.

Hitler, probably. I feel like that might be quite bad.

When both people in a relationship are in the leadership of an organization, it's a serious problem when one of them cheats with someone else also in the leadership of that organization. A friend of mine was part of an organization where this happened, the drama was terrible.

Stalin

Her Grandfather.

Her sister. They're close, and it would be devastating to her.

Piers Morgan. Sucks to be cheated on, but imagine he was the one your partner preferred. That shit would stay with you for life.

Their ex after me, I would suppose. That'd sting.

I'm torn between partner's family member, partner's best friend, & partner's ex.

The answer is…. D) all of the above/ and below!

Kim Dot Com

Anyone, but also 2x anyone with an incurable std.

The Pope

Your brother who your a conjoined twin with

There's only one right answer to this question and it's the one person that will make him/her feel stupid for trusting you, AKA "the friend you told them not to worry about"

Their sibling, or parent.

Sibling definitely.

Your partner, disguised as another person.

You cheated, except you didn't even actually cheat.