Hi Gordie - just about to go into a boring conference call and saw your post.
Setting aside the emotional issues for a moment you know that she has most likely been having unprotected sex with men whose history you don't know and who quite probably she should not have trust in. Nothing you've posted has indicated that she has gone to get tested. If sex does happen - protection will be necessary.
As a LOL and as an indication that you are open but concerned, just get a box of condoms and put them on your night-stand. Either it will open a conversation, or it won't. I believe (and hope) that they have a long shelf life. I think my (completely unused) box has been on my dresser for about a year.
Since I love pressing analogies far beyond reasonable bounds, let's say that you sweep everything under the rug which is the most likely direction of you are both passive about this. If you have pile of unknown junk under the carpet and then try to build something on top of it, it will never have a solid and stable foundation.
This "can" work but you'll never be able to relax because it could all come falling down at any time.
I'm sure I'm not saying anything you've not known already for a while.
How best to deal with this? I have no clue but you've got some smart people around you IRL I believe who know more about this than I ever will.
#TeamGordie
On BD H52, W50 T27, M26 S21, D23 BD-9-Mar-16 D-15-Jan-18 Final-19-Apr-18 I am a storyteller. The story may do you no good. But a story is never for the listener. It is always for the one who tells