Long story short,
We weren't able to crush TBW stack (Should have whipped harder really, that's the lesson of this game), because of lack of numbers (despite being number 1 in power since 20 turns or so now) and elephants/xbows defending for TBW.
But I didn't do anything silly and did not sacrifice our boys for nothing.
Since I heard SD was about to revert alliances and attack us (the fool!), I did it before him :D
Gave back Herpes to TBW and took Malaria from him instead, opening a path into the Incan land. Meanwhile, SD had understood what was going on (when he saw we didn't kill ourselves, TBW and I) and declared on TBW.
Now we are at peace with TBW, and I declared on SD last turn. Took Mesa Verde from him (former Gavagai's city) and I am pushing west.
Not sure we can make it (his stack of knights is massive), but we had to do something (SD is running away in land/techs since he took all Gavagai in few turns...).
Our economy isn't in great shape since we have so many troops in foreign territory, but either they will die, or I will use capture gold to push to nationalism/rifling.
Anyway, here is an overview: