こっちの話
Meanings
1
our conversation; private matter; none of your business
Colloquial phrase used to indicate that the topic is a private conversation or matter, often to dismiss someone's inquiry. Can be used defensively or to set boundaries.
See also: こちらの話
"What are you talking about?" "It's a private matter, so don't worry about it."
That's our business. It has nothing to do with you.
2
our side of the story
Used when contrasting one's own version of events with someone else's account, emphasizing that there is another perspective.
I want you to hear our side of the story, not just his version.