Sounds like brutal surgery to go through and I imagine your body will take some time to fully recover.
There is a lot of good advice above including not over training but I’d also suggest some meditation to help give the body the best chance of healing. The theory being that by calming the mind, even just for 10 mins a day, will help with getting better sleep and generally putting your body into a better position to heal itself faster.
I got switched onto it after being diagnosed with fatigue following a viral infection compounded by over training, it massively helped me reduce the mental tiredness and get back to cycling again. (I was a complete non-believer before)
Check out something like Headspace I think they are still doing a free trial. Worth trying if you are eager to get back to full fitness.
Wishing you all the best.