I think you could certainly have lunch with her again some time if you feel like it. If again, the conversation turns to serious or uncomfortable topics, you could try a large shift to something entirely different (such as films or books) or simply say: "I'd like to just enjoy a nice lunch and chat about light topics." You could pay this time to return the favor or each pay your own way. There's more than one way to move forward. You didn't do anything wrong Ennie. You are good