I had it. I've had all kinds of depression over the course of my life but this one scared me the most. Like you, the one thing that kept me going was DC and I lived in genuine terror of waking up one morning to discover that I felt indifferent about them too. Luckily that didn;t happen.
I found an odd cure for it. May not work for you but worked for me and has worked for other MN-ers I told about it.
It's quite simple: Do something you have never done before in your life every single day and record how it went in a diary or private blog.
You can start small. Try a new veg or fruit, explore a nearby street, order a different coffee from a different cafe etc. It's important to keep a brief record. Can just be: 'tried a pumpkin latte today. too sweet. Not for me.' Or it can be more detailed, especially if it is something that made an impact on you.
Try to include things that get you out of your comfort zone. Things that scare or embarrass you a little bit, or that you think are stupid or silly or childish.
I think it works because our brains have to find new neural pathways to process this sudden influx of unfamiliar activity and it stops us from using the same old neural ruts we've got into. But it also stops us from living in a rut. It reminds us that there's a lot out here in the world to appreciate and experience and try and enjoy.
I got inspiration from online bucket lists and comfort zone lists and also write my own bucket list of stuff I'd always wanted to do, maybe from childhood to now.
It's important not to hope it will make you feel better. Just do it and record it. I found after about six weeks I was taking an active interest in the project and after three months I woke up happy, really happy, and have stayed happy more often than not ever since.
If you want to try this and want some links to online resources to get you started, let me know and I'll share some.