IMHO these are to completely separate issues, and the women who wrote the letter did nothing but a complete disservice to those who are in favor of the RC allowing married priests.
Issue 1: Celibacy vs. married priests-- I personally believe that the RC should allow married priests (and not just as an exception). But that's just me...
I must say that if it is true that the Pope said that celibacy is "the sign of full devotion" and of an "entire commitment to the Lord," that really ticks me off. It is ridiculous, in my opinion, to think that one cannot fully devote themselves to the Lord and be married at the same time. Look at St. Peter himself! He was married! How could anyone possibly say that he did not fully devote himself to the Lord? If a married person is martyred for the Lord, does that mean that their martyrdom is less than full devotion because they were married? Ridiculous! This is bad theology, because it sets marriage up as an IMPEDIMENT to full devotion to Christ. I would think that if Christ thought marriage was an impediment to a relationship with Him, He wouldn't have blessed it.
Issue 2: The affairs these women and the priests had-- I'm not going to judge anyone for the mistakes they make, as who knows what may have led them to those mistakes. But, I feel sorry for them in thinking that the RC is to blame for their failed relationships (which were, frankly, doomed to fail from the start) because of not allowing priests to marry. The one really has nothing to do with the other. Infidelity is infidelity, and as Handmaiden said to begin with, they were engaging in sexual relations outside of marriage. Period. End of story.