Tuchel is actually very stressed by this result. However, so far, Bayern Munich has always been above Dortmund, even though sometimes they are behind, but in this match. it's really outrageous, the results are very bad.
For the first time in 10 years, Borussia Dortmund were able to take all three points in a Der Klassiker game that was played at the famous Allianz Arena and the statement of Bayern Munich manager at full time simply suggests that he's already conceded defeat in his club's battle to win the the German Bundesliga title for the 12th time in a row. 
Source: Bayern Munich vs Dortmund
As for Leverkusen, there is no doubt, it seems like they just have to enjoy the performance of other matches while waiting for the finish time to still hold the trophy. But what they do best is, they never give up, and they continue to show their best in every match. Even Leverkusen still maintains its unbeaten title to this day.
Now is the time for Tuchel to congratulate Leverkusen on their achievements this season. Even though the season is not finished, the 13 point difference in the standings can speak, meaning that the competition for the trophy is over and Bayern has raised the white flag in surrender. Leverkusen only need 3 more wins to lock up the Bundesliga trophy, and they will change the history of the club.