I don't have any really good advice, but I feel the same way about responding to contacts. I don't contact H at all (unless I have to do to the kids). But he has been reaching out to me lately about kids, his life, stupid stuff. I try not to respond immediately all the time, but I generally do respond at some point.
My H has said that he started his EA because he did not think that I was supportive and he did not feel needed. As a result, H stopped reaching out to me and stopped filling me in on the events in his life. He went to OW instead. So when he reaches out to me now, I have a hard time not responding.
I think that you can respond and validate without being her emotional support. It may take a bit to find the right balance. Maybe just pick and choose what to respond to based on the contact of the message.
