Q: "Am I reading to much into this or does she want this other man to become sexually interested in her? "
A: For the time being, you may be reading too much into this. A motivation of hers may be to perhaps feel better by showing off her shape. If these are decent pictures, sharing them from someone from her past, may also be a way to taunt this ex.
Their interaction/relationship is 40 years into the past. As an individual she had changed not only physically but psychologically.
Unless you find out more to show that their interaction is not within the lines of platonic friendship, try to give her the benefit of the doubt. If she intends to become unfaithful, she does not have to do it with someone in another state from her past. She could do it in her hometown w/ a current acquaintance.
Of course, as her husband, you have the right to tell her what you find decent or inappropriate interaction and ask her to not do anything she would not want you to do.
You know your wife well and what she's capable of and how trustworthy she is as an individual and a wife. If she had broken your trust at some point in the past, it makes sense that you would be more alert now. If nothing had transpired throughout your marriage showing infidelity, then try to see where this leads. Your reaction may be as a result of the ED and your own fears rather than her actions or intent.