Major forces that UPA fought were NKWD and Nazis, not Poles. So by trying to keep Ukraine shut about her army and its heros won't lead to any fruitful resolutions.
Yes, because Polish villagers had no forces, only lives. And how many Germans and Soviets UPA eliminated comparing to the number of defenseless Polish peasants killed. I'm sure that the latter number was greater.
It is equal to saying: "you didn't defend your land against Nazis and NKWD and you didn't have an army, because Poles in Wolyn were killed by UPA or Ukrainian peasants".
Yes, you did. Very effectively. You have your western regions almost totally wiped out of Poles. But we are talking about the methods. It cost your nation very much but you have your frontiers wider - almost 100% of your prewar nationalist plans. But it cost Poles living there few times more.
I hope relations and their reasons, which our nations had to go through in Cossack era
I think you should also try to look at your Cossack hero Chmelnickij (artful and outstanding but ruthless political player in his historical context) from the other perspective. His rebellion killed probably more Ruthenians than Polish forces did in response.
But - in any case - Poles are trying to choose your heros. There were many valuable figures which probably could qualify. Some even of Polish descent like Antonowycz, Hruszewśkij or even £ypynśkij and Szeptyckij. But it is, of course you choice. Poles know it, so don't try to say they don't. Poles are just angry when you build monuments for and make hero of guys who should be first denazified before putting them in school books.