Happy New Year to you too.
That is great that Haydon is having his stoma revearsed in March. Obviously, as he is again having surgery, then no surgery is without risks, but remember that when he had the last surgery he was very sick beforehand, which is one reason why he was so unwell. If you are that sick beforehand, then your resistance to infection is lowered. However, I suspect that he will be a lot better and healthier now and even better in March, so he should recover more quickly, as he should be better nourished and in better health. Obviously, with surgery such as this you can't say that he won't get peritonitis again, but there should be less liklihood of it happening this time.
When they revearse a colostomy, the loop of gut has to be pulled back through and anastamosed to the rest of the colon. A five day stay sounds reasonable to ensure that the wound is healing ok and that he has no other problems with his bowels. He will have to get used to having his bowels open normally again whilst sitting on the toilet and this may take a little time. He may take longer on the toilet than is normal at first until his bowels adjust and he needs to avoid constipation, as his belly will be sore after the surgery and constipation will make this worse.
When he gets home, he should be ok with a little help, but the nurses on the ward could always arrange for the District Nurse to visit on a daily basis to check for any problems and give a little extra help until you get back on your feet again.
Hope this helps and good luck?
P.S. Can they not do a vaginal hysterectomy rather than having to cut your tum? The pain and recovery time are greatly reduced with this procedure.