Never second guess your feelings or try to talk yourself out of how you feel. Treat these naked breasts as messengers that are telling you to find out where your feelings are coming from.
Most women in our society are threatened by younger, more attractive females, because we have been raised to feel like the sum of our various parts. And, as we age, and our parts sag, we become worried that our mates will trade us in for younger models.
So, your feeling threatened is something that every woman in this culture can relate to. This may become the occasion for you to do some self-work in which you come to treasure all your wonderful internal (not just external) qualities.
When you are done with your own personal examination, study your relationship. Is there something nagging at the fringes of your consciousness? Do you sense that your husband is unhappy with you or some aspect of your relationship? Do you sense that he will cheat on you because he is far from home?
Once you identify where your concerns stem from, speak to him about them. If he admits that he has issues with you, then address and resolve them. It is likely that your concerns are fueled by the distance between you.
With him so far away, he can't as easily remind you of his love and devotion to you. And, perhaps your fears are telling you that you need more contact with him. You both can talk about how you can strengthen your connection during this difficult time. Love letters, audio tapes, etc. ?
Bottom line, thank heaven for the naked boobs that were sent as messengers to heal your self-esteem and/or marriage.