I would not be able to kill my own brother no matter what! Couldn't Michael have sent him to Italy to live?

Good Point

In GF1,Michael warned him never to take sides with the family again.And he did,Michael never gave anyone a pass,not even Family

It shows how cruel he really was.

Even if he had to kill him, like he did. How could he watch it?

FFC probley wanted him to watch it as it would make the film more Dramatic(is that the word im looking for)

If you think about it everything comes down to trust. In the last chapter of the book when Tom is at Kay's parents house, Kay asks why Michael could not forgive and forget Carlo. Tom answers her by saying that treachery and betrayal cannot be forgiven and to let the betrayer go on living would be to forever endanger the family. Because the betrayer would never be able to forgive his or herself then they would always be dangerous and therefore the only way is to eliminate them altogether. And as far as Michael watching I believe he did this for two reasons, first to make sure it was done, second because he knew what he was doing was horrible and he wanted to punish himself by watching the act.

I believe michael was quite comfortable with the idea of killing his brother, but even at the time of killing, he knew it was wrong and bent his head down in guilt when he heard the bullet shot.

You can read also many interesting things on this subject here
And also here.

Micheal is pretty messed up about killing Fredo in Part III though, because when he takes his diabetic fit he yells "Fredo!" Its like its eating him up inside...

I don't think murdering Frederico made Michael any more sinister. If Frederico had already attempted to murder him, why was it so wrong for Michael to retaliate?

Fredo allowed for Hyman Roth's people to get close enough for then to try a hit. After Michael gets proof of the betrayal, he still offers Fredo a way out of Cuba, which Fredo refuses. The first thing Michael asks Tom when he gets back to Vegas is where is Fredo, and then Michael tells Tom to get word to him to come back to the family, and that he understands Fredo was misled. It is not until Mike and Tom discover that Pentangeli is still alive that Mike confronts Fredo in the famous "I was passed over,"
scene. It is in that scene where Fredo tells Mike that he has additional information that the Senate lawyer is on Roth's payroll. This means Fredo had to have known Pentangeli was alive, and despite all he was still operating behind Michael's back. It is then that Michael tells Fredo that he is not a brother, not a friend, that he is banished form the casinos, and that when he comes to visit their mother he needs to know a day in advance. It is that moment when he decides to kill him, and it is then that he gives Neri the order "I don't want anything to ahppen to him while his mother is still alive." Of course after mama Corleone dies, Connie promises Michael that she will stay close to him if he will only forgive Fredo, which he pretends to do. He thus allows Fredo back into the estate, keeping in mind that you keep your friends close but your enemies closer.

DonTomasso, I agree with you that michael decided to kill Fredo much later(probably during the "I was passed over" time) and not in Havana. Some members on this board feel that michael asked Fredo to join him on the plane so that he could kill him later. But I think that if he really followed the principle of "keep your enemies closer" Michael wouldn't have revealed to Fredo that he knew Fredo betrayed him("you broke my heart" scene). Michael was (a) truly upset and was not composed enough to be strategic at that time, and (b)He really did not have enough information of how deeply Fredo was invloved in the betrayal.

I should also thank you for incidentally answering one of my doubts, which was, why did micahel choose to forgive Fredo at the funeral and then kill him? I think he was using his "keep your enemies closer" principle now that he got enough time to analyze the betrayal.

SVSG note that when Michael "forgives" Fredo by hugging him at the funeral, he is looking straight at Neri and nodding ever so slightly, as if to tell him that the time for the hit is coming because mama is dead.