My suggestion is to give yourself an official 3 month break...no guilt, no questioning and definitely no riding
I've more-or-less had that through illness.
I think maybe my answer is to not think about it, just head out with no expectations and see what happens. If I get 1km down the road and just turn and head home then so be it. That said, it usually takes me a good half hour before I'm feeling it - so it'll be a slow 1km then!
There's a ride I do, around 60 to 80km all told depending, that's absolutely brilliant this time of year. I suspect, in the back of my mind, I'm aware that I'm not up to it and that's possibly saddening me - making me think it's all over. Yes, I am a catastrophy thinker!