I think that you mean the 4th Crusade rather than the 7th. Although they started out as crusaders they were diverted from that task by the Byzantine Prince Alexios IV Angelos to act as mercenaries to reinstall his father, the deposed Emperor Isaac II, on the throne. The Latin empire in Constantinople was only established when Isaac and his son were deposed again the Latin mercenaries return to take the city in order to receive their promised payment.
To continue to present the actions of the former crusaders in establishing the Latin Empire as a perfidious action of the Latins/Catholics against the Greeks/Orthodox is to misrepresent history. The Eastern Empire was weakened by internal strife that had been going on for centuries. While the actions of the Latin mercenaries who were brought into the dynastic disputes of Constantinople by Byzantine princes exasperated the situation, it was not the cause of the fall of Constantinople. Additionally, to continually harp on this is to isolate the aid that the Eastern Empire also got from those Crusaders who fulfilled their mission and fought the Turks to protect Christendom. It is time to declare history to be history and not bring up old wounds for the sake of modern polemics.
“I think that you mean the 4th Crusade rather than the 7th.”
You are of course correct. In my feeble defense, I can tell you that ten minutes before I wrote “7th” I had been discussing the 7th Ecumenical council with a friend and the priest apropos of some of the icons at church.
I will stick with my assessment of the actions of the 4th Crusade. As you know, +JPII apologized for what they did. It also lead to the establishment of a “Latin Patriarchate” at Constantinople (and others throughout the Orthodox East, even in my family’s part of Greece, Morea) which were quickly recognized by Rome at the 4th Lateran Council. If I remember correctly, that Patriarchate was dissolved in either the 1950s or 60s!
These are historical and present day realities which may make little or no difference in the West, but a meaningful in the East.