No offense SC, but I think that LR and Samaki have gotten past this and are now understanding what the other was saying, as explained in posts 5 & 8.
Now back ON TOPIC:
Nelara, as the other posters have stated, you have every right to be upset. Not only did your husband show disrespect for you, but also for your relationship by having unprotected sex without your ok.
Why did the GF break up with her SO? Not to sound paranoid, but is she using you both to have somewhere to possibly stay? Were you two a way out for her? Put your foot down if you are unhappy. It will be hard, but you have every right to say "No, I don't want her living here at this point in the relationship," then give some reasons, including the unprotected sex and disregard for your feelings, but also, how well do you know her and her circumstances? Can she pay rent or is she assuming that she will be taken care of?
Always remember, you don't have to sleep with the same people your hubby sleeps with. It's not mandatory to be considered poly, whether you are hetero or bi. If you don't feel that way for her, then you don't.
Also setting up boundaries and/or agreements is a very good idea. You both need to know what the other wants out of poly and even out of your own relationship. Without that, things like this can and probably will continue happening. Be strong, you CAN do it.
Life is about the journey and not the destination,
so what better way to know life
than to wander all the roads and paths set before you.