Why am I freaking out about this?

I honestly know how you feel. It seems like the end of the world at the time but it's really not. I'm willing to bet that no one has really noticed. To feel better all you have to do is get back in your old routine! If you enjoyed running it will be easy for you. Start out slow, go shorter distances and as you feel you're getting back to your old routine you can go for longer. Go buy some ankle weights and run with them, do some easy workouts at home and such. Your body WILL come back if you put in the effort. It's gonna take some time, but if you want to get back into your more fit and healthy lifestyle it'll be easy. :)