look I'm a wehraboo too, but the Germans only advanced so far because of their good experienced commanders. They had inferior Panzer 3s and 4s and were heavily outnumbered. It was inevitable. They had already lost air superiority to inferior Russian planes as well. also no Supplies.
I think you are wrong. Russia would have defeated Germany with or without help. as Germany pushed each line, a smaller layer would be added to the next defensive line, and this continued, making the last defense line Unbreakable. This broke the German forces.