all is not lost!!! the wight will come off with your consistent riding ahead, so don’t freak out.
it’s almost july, so look for an event in late August or September; you have 6-8 weeks to be better than you are now.
Sure, being derailed like this is no fun, but it’s life and the fitness gains you made WILL COME BACK.
I’d just start ridining consistently for 1-2 weeks then ramp test and jump into a speciality plan based on your august/sept goal.
Let us know how it goes!
I´ll keep posting here just to keep track of my progress 
After two weeks of leisurely riding my MTB bike outside, doing small and flat loops of 35/40 km, got back to the garage and took a Ramp Test. Surprisingly, my FTP nowadays sits in the 250W ballpark, only 30W below my last test before the break.
I´ve broken a golden rule by skipping base and build, setting up a XC specialty programme, but I only have July to do structured training as I´ll spend August away in the beach.
So things are better than expected! Thanks!!!