Poland must look inward for it's strength and revitalization, and make careful, tactical
I don't believe anyone sold Poland out. In WW2 Poland managed one key victory. That was to get the Western Allies into the war. Poland held out long enough to get France and Britain to declare war on Germany as per the pact Beck had setup among those 3 nations. German plans were really to expand eastwards and not westward, Germany was not a threat to Western Europe (Britain and France). Hitler did not want a war with Britain and France. On the other hand Stalin wanted Germany to weaken herself on Poland so that he could move in and crush Germany and have both Poland and Germany for himself - then the rest of Europe. Suffice to say Germany did not wear herself out (too much) on Poland as the Polish armies were ordered to retreat strategically in most cases (ultimately to the West), or to disband and form the AK. You could also say that Hitler was also in an unwinnable situation. He could only attack the USSR as Stalin was building up his armies to take on Hitler. Hitler's only chance was a swift defeat of the Russians ASAP hopefully on two fronts, hence he declared war on the US after Pearl Harbor to get the Japanese to attack the SU, but they weren't stupid.
However after WW2 no-one expected the West to fight the USSR over Poland.
The West was too scared of Stalin, as the Red Army at that stage (1944 onwards) was
unstopabble and had they tried, Western Europe would be speaking Russian now.
So yes Poland has to be careful and needs to make alliences with more distant countries
as I wouldn't trust either the Germans or the Sov.... ahem Russians.