Gossiping about my dad

I have a very firm stance on gossip. My sister-in-law has opened up to me recently about her issues with my father. I want to be supportive and help her feel validated even though I know that she is creating most of her issues from her thinking. I also know my dad tends to be abrasive and not even remotely tactful at times and generally offends others. His own children, including myself, know that he’s just REALLY quirky and so we aren’t ever offended by him. Most all of the in-laws, on the other hand, have been offended by him and seem to continue to be offended by him.

Anyway. I felt guilty even discussing issues about him with my sister-in-law. I usually just defend him and explain him to other people- as I’ve done my entire life (he’s VERY quirky etc), but this time I kindly and patiently listened and listened and listened to my sister-in-law and agreed with her that yes he can be very abrasive and very untactful. I could tell that it helped her so much and it felt good to listen, acknowledge, and understand her and help her understand me too.

But now I feel guilty and I’m not sure if I did the right thing or the wrong thing. How can I know if when it’s appropriate or not?

I think I’ve been so staunch in my opinion to not gossip or even discuss my parents that I can tell that my sisters-in-law have felt like I don’t understand them and it’s so important to me to feel like I’m one of the “sisters” as I have 4 sisters-in-law. I love them all very much and look up to them in so many ways.