Ok, so it turns out I couldn't go back to my save right before going to Tuchanka because I'm an idiot and already saved over it. At least I'm only missing out on a few Citadel fetch quests, so nothing tragic.
Garrus, Liara and I went to Grissom Academy to check out the situation, and Cerberus is trying to kidnap the biotic kids. Not soon in we met Kahlee Sanders, and I promised to get the kids out. We went along, found the first students and sent them to safety. And then we met Jack, she's the kids' teacher! Would've never expected her to do something like that, but I'm positively surprised and the kids seem to like her. Jack greeted me with a punch in the face. Well thanks. But she looks good, and we exchanged a few sentences, then went on to business and got rid of more Cerberus (again, grenades are not my friend, and neither are turrets apparently, walked in one's sight and paid the price
). Then we met David Archer again, nice to see that kiddo doing so well. In the next area I boarded an Atlas and everything went wild, that was fun! Everyone made it out and we can use the biotic students for a support role in the war.
Then EDI, Liara and I went straight for the Citadel, to fight more Cerberus. These guys are NOT annoying at all 
Thane is on the move too, and we cleared out the first area of C-Sec HQ, then talked to Bailey. We proceeded until we eventually found the Salarian Councilor, who claimed that Udina is somehow involed, but an assassin is onto him. In came Thane and they had a fight, and the drell got critically injured while that man fled. Damn, Thane, that doesn't look good, you got me really worried there.
We went on to find the Council, getting rid of more Cerberus goons. We ended up taking an elevator top as our ride, taking enemies on as we went up, then I jumped on the elevator in which the Council is currently getting away. Someone shot at me (Gee, Kaidan, watch it!).
It all led to a showdown, and then Kaidan and I stood opposite each other, weapons drawn. I don't want this! I lowered my gun and explained how this is all Udina's doing and that Cerberus is waiting for them right behind the door we just sealed. After a few intense seconds Kaidan put his trust in me and pointed the gun at Udina. Udina knocked the Asari Councilor down and pointed his gun on her. Kaidan shot him and I ran over to him. He said he's good.
The door behind was breached open and out came Bailey. Apparently all Cerberus activity seemed to have stopped. Back at C-Sec I asked Bailey about Thane and went straight for the hospital, but it looks grim. Kolyat is with him and he finished a prayer for him. I joined in while Thane... Goodbye, my friend, it was an honor to have fought by your side. Now excuse me, but there's something in my eye...
On my way out I met Steve, hanging out in the docking bay. We had a talk about starships, and the topic once again went back to his dead husband. Steve might do something on the Memorial Wall for him, to finally let go.
Kaidan waited for me at the Normandy, and we talked about what happened. We put everything behind us and he let me know he will never doubt me again and has my back. Thanks, Major. And now move that ass of yours back onto the Normandy, you were sorely missed.