I think your story has an analogy to an experience I've had once, so I'll share it whatever comes of it in hope of helping.
I was on hrt for 8 months, and I had decided to stop it and return to my 'former' life. Now, I haven't felt depressed for a single day while on hrt, but gradually as I reverted to my old habits and modus it all came back flooding in. To say it was overwhelming would be an understatement. Now, the fact that there was some amount of estrogen in my blood (although I was on lowest possible dosage) may have aggravated the issue (I imagine it's multifold worse for you if you're on regular dose), but that's not the point. I was depressed like never in my life and it was the clearest sensation you could imagine. But, I didn't indulge for too long, but (by pure accident) took up my writing and, by slow degrees, it became easier. In some time, I have realised that I can function just as good as I've functioned before, in the 'former life'. I have realised that this depression was ever present there (in my pre hrt-life), it's just that I put a HELM on it and never minded it.
Now this is instrumental. If you aren't able to put reins on it and find a modus that you can function with, of course your emotions will roam free and who knows what will come to your mind. Just adapt to it; find a mindset that you can function with, and convert that negativity into your strength. That's all I can say, hope I did anything towards helping you.
Kind regards,
Vanya.