I'm planning to move in with my best friend's ex. They just broke up a month ago.
Why do you want to move in with her?
She and my friend are broken up now and she's really into me.
I understand being flattered that someone likes you, but have you considered your friend's feelings. I'm sure they would be upset if you moved in with their ex and started a relationship with them. If you care about your friend, you should distance yourself from this girl.
I don't think he would mind. Even if he does, he doesn't have time to think of me.
Your friend probably will mind, even if he says that he doesn't. Part of being a good friend is being loyal, and you're breaking your friend's trust by dating his ex. Think about how difficult it will be to maintain your friendship if you're dating his ex.