Here's just some comments from the peanut gallery.
He's depressed, and this is killing his determination, and ambition. He is stuck so deep in his own pit of self pity that he can't see himself succeeding at work, school, or even his personal relationships.
This is something only he can affect. He has to hit rock bottom, and then from there decide he wants things to improve. Sounds like he is still to content with just getting by or worse watch everything he's ever wanted slip away.
I suspect at some point you subconciously realized this, and started nagging him in the hopes to get him moving. (I infer this from his complaint that you were too controlling.)
At the same time you were too afraid to leave, and rather than improve without him you chose stagnation for yourself too. It soothed his own inadequacies, while providing an excuse for you to not outpace him and be disapointed in him.
Now that you are improving himself it is proving his inner fears that he is not good enough for you, and was probably a hinderence all along.
Expect him to get worse the better you get.
He needs to get to the point where he says:
"I deserve good grades"
"I deserve a good job"
"I deserve Jenna"
"I WILL fight for all these things"
If becoming a strong man is his end goal, then he needs to start on his journey.
You can't drag him along, and must continue on yours. If you decide to get off the path to cheer him on you'll find that he may never get on it. He has no reason to, you are already there with him.
If you continue on the path and he sees himself left behind then he may finally get the motivation to get up of his feet and chase you down the path.
Keep in mind that there is a chance he decides to never take the journey, or once you get going he may never catch up, and you may not want to slow down for him
