Don't feel like a wimp and only do what you can! Do not push it and realize your body needs to rest and recover still.
Take it from me, who did not listen to people's advice last year and tried to push through while suffer through illness.
Take every little thing and enjoy it
go ride slow, look around at the scenery, take in sights you might of passed hundreds of times but never noticed.
Also maybe think of adding in a form of cross training?(yoga was a huge help for me, even if it was sometimes just a yin class)
But on a positive note, I dealt with Lyme and Rocky Mounted Spotted Fever just a little over 2 years ago(june 2010 I contracted them) and it took me until nov 2011 to be able to start feeling great. I would feel good, then work out to hard and end up being really sick(went through EBV and a few other side issues due to me not just taking it easy). I am now almost as strong as I was before I got sick and definitely take more enjoyment out of being able to do the activities I do, because I realized how lucky I am to be able to do them.
Welcome back and take it slow, no need to take 2 steps forward to take 3 backwards. Just enjoy the little you are able to do and realize that up until now you couldn't even do that! And time will go by quickly and soon enough you will be back to doing 100 mile rides