The visitors were 4-0 down inside 25 minutes at Signal Iduna Park on Saturday and facing up to the prospect of a first loss since September.
But Tedesco, overseeing his first derby at the helm, witnessed a remarkable comeback inside the final half an hour, with Guido Burgstaller and Amine Harit cutting the deficit before Pierre-Emerick Aubameyang saw red for the hosts.
Sensing their chance, Schalke piled pressure on Dortmund and got their reward with Daniel Caligiuri's 86th-minute goal and Naldo's stoppage-time leveller to cap a stunning comeback, leaving Peter Bosz's BVB future in severe doubt.
After a breathless encounter, Tedesco said: "It's difficult to analyse such a crazy game. Both of us head coaches will need quite some time to cut out all the errors made by both sides in this game.
"If I'm totally honest, I didn't believe we'd come out of here with a point at full-time given our first-half performance. Therefore, it feels even sweeter. From a footballing perspective, our second half was magnificent and I can only praise the players for that.
"Dortmund overran us to begin with. Every shot they had seemed to go in. It wasn't easy to get over that quickly. The fact that we did that is incredibly impressive.
"To be 4-0 down in this stadium, in this atmosphere, after 25 minutes is simply hell.
"In the break, we gave ourselves the target of winning the second half. The fact that we came back and got a point is unbelievable. We've shown we have the character and mentality to put on a spectacle. I'm very proud of the whole team."