Ladies...talking abut past relationships... OK or not?

Your not being sensitive, no one wants to hear what their partners ex's were like but what you do need to know is that they are ex's and probably for a very good reason. Talk to her again and explain that you find it upsetting for her to talk about her ex's and that you feel like she is comparing you to them. She could be just trying to make sure that you don't make the same mistakes that they did and that's why she's telling you how it went wrong with them, kind of a security device. Either way you need to talk to her again about it.