just adding my own littel .02 in here. I would maybe not ask her to have a test but I def. wouldn't have sex with her until she did. If she loves you, it would be something she would do on her own...without being told to.
LSS had numerous affairs during our time together, none that I knew about and obviously wasn't safe because I tested myself after he left.
I agree with Bworl...you need to build a new relationship and then when that relationship is established, you would want to have that talk.
Jack is correct...it's a health care issue and if you have children, it's also something even a little deeper. So, I wouldn't be having sex until a new relationship was established.