Don't usually post here, but have been there, done that, learned my lesson.

I worked in HR for over 20 years. I zero'd in on the fact that even if your friend "Joan" gossips about her own mental health, she has a leg to stand on if she can prove that you have been gossiping about it. In the workplace, someone can gossip about themselves all they want, but if someone else does it, it can cause some trouble.

I agree, women can be catty but I have learned over the years that extending professional "manners" even if the person doesn't respect their own privacy, helps.

Also, the questions your HR has asked you can be valid, but they don't have the right to ask if you did something outside of the workplace unless it's criminal...you might want to check with a lawyer on this. Sometimes they will talk to you on your first visit for free or perhaps there is a legal clinic in your town?

Anyway, good luck to you and keep us posted.