You’re reading to much into it, when it comes to the size thing. It doesn’t sound to me like she is implying that… if I was on the other side of the conversation, I’d just believe that you guys don’t use condoms. She didn’t go into details: you did, in your head.
As for talking about sexual past… I don’t know… it really depends on your relationship I suppose, but people I hang with are not constantly trying to hide that they have a sexual past that involves other people than their current partner. Then again, I generally hang out with sex positive people who are not shy about talking about sexuality, so there’s that.
Either way…not everyone has the same preconceptions of what is appropriate or not regarding those things, so I wouldn’t see it as disrespectful if I were you… but you absolutely can have a talk with her and tell her in a non accusatory way that it made you awkward.
how does she know the friend could use that size?
Maybe she’d forgot about them, didn’t want to waste them, and thought it would be best to be honest and above board about it. In which case she would need to explain why she had them, which she did.
Isn’t that less weird than privately giving out condoms in secret as if there was something to hide? The friend may have ended up telling you after anyway if she did, and I expect you’d have a problem then too.
Don’t worry about this time. Tell her specifically what you didn’t like about this situation and why, and then only have a problem if she doesn’t listen to you and does it again