It might be a little bit brutal, but next time they start over sharing don’t respond. Simple “mmhm” and/or changing the topic will do. You can always just abruptly walk away. I think the baseline is not to engage in the conversation. Just to clarify; don’t be rude, but send a strong message that you don’t want to talk about their problems at this time. They should quickly notice that you are not willing to participate. I’m sorry you have to deal with that. Setting up boundaries are important for every person, and you should take this as an opportunity to learn/practice how to do it properly.
Good luck!