When making a comparison to something that was just said, you should generally match the way it was said.
In your first example, "Yesterday I went to the wedding." -> "Yesterday I was home playing games." It's not strictly required, but repeating the pattern is a good way to emphasize the differences.
Your first example also sounds especially awkward because doesn't really follow from the line before either. It is not connected to the activity (you didn't go to the wedding), and it's not contrasting with it either (you did something else at a different time). It's all grammatically correct, but it is a sudden change of topic, which comes off as mildly rude:
A: [proposes a topic]
B: Oh really? [talks about something totally different]
Your second example is subtly different, and reads much better:
A: "Did you hear about ____?"
B: "Yes! _____ affected me too!"
Here, your use of "after" implies a connection that was missing in the first example, so the conversation continues more naturally.
Although it parses fine, "the incident" sounds slightly odd, because "incident" is often used with a touch of irony to refer to some past bad thing that will not be explained. For example, the old, popular comic strip Calvin & Hobbes referred to "The Noodle Incident" to explain why Calvin was not allowed to do some things, but never explained what had happened during The Noodle Incident. Instead try "After that happened," or "after I heard about it."
