Don't worry. My friend's son also got the same disease when he was borne. He took the surgery in his few-months old and he's so healthy now - nearly 5yo.
Also you'd better to strengthen his body by doing exercise like hiking & swimming after he/she recovered.
Regarding abortion, you'd better to take doctor's advice. It would be too cruel to lose such a 5-month babe! Maybe he's such a tough kid.
We are so sorry to heard about that, but don't worry. My daughter also got the seriours heart discase when she was born. After she have the operations when she was 4 yrs old. She is now no difference from other children. Let me answer the questions below:
1) The doctor will advise when she is suitable to have the operation. Usually, the operations will not be taken for a new born baby. The operations will take until the baby grow to the suitable weight.
2, 3 & 6) The baby of course need to take special care because he/she is very weak. i.e. the baby is much difficult to take care, he/she will catch discase easily and always got chest infection.
4) The baby can do exercise but cannot do too much.
5) Yes, the baby can 100% recover depands on the operations.