There must be at least a dozen topics in this forum related to creating private chats. It seems to me that there needs to be a “chat” component. I envision this working exactly like the comments thread component, but with the interface of the chat screen. This chat component would let you choose a topic just like the comments component so that way users of your app can have an individualized chat experience.
The benefit of having a chat component over a comments component is that the chat component would allow you to have a UI that mimics a chat with users on opposite sides of the screen when they post / respond, automatically scrolling to the most recent message, Etc.