Well first thing is keep positive as hard as that may be because that will have a profound effect on your well being. Sounds like you have been through a lot and are eager to get your life back on track but your body isn't responding or rebounding as fast as you would like it to after your ordeal. I would definitely speak to your GP who is familiar with your situation and see what he says about this. Sounds to me like you are possibly trying to jump into an intense training regimen a little too quickly and your body is shutting down.
These are things I would try first:
1./ Overhaul your diet. Look at what you are consuming and rework it. Start by making sure your body is getting everything it needs to get well and try removing the things that could be slowing it down like processed foods, sugard, sodium intake. Try getting more complex carbs, lean proteins, lots of fruits & veggies and fresh fatty fishes.
2./ Mild activity: Try swimming. Excellent cardio exercise and works every part of your body, also low impact. You can also increase the intensity as you see fit.
3./ Low intensity body weight exercises: Pushups, chinups, dips, crunches, lunges..etc. all the while listening to your body and making sure you don't push it too hard.
4./ Time for yourself to rest and regroup. Get enough sleep, find ways to deal better with stress and work the above steps into you weekly routine.
That's pretty much all I can help you with in terms of working a healthy diet and fitness routine back into your life. Just take it slow and eventually you will get back to where you want to be. Your body has been through a lot so it needs time to adjust, give it the time it needs and I think you will be ok.
Good luck..