SOILERS: After the end-question - please help!

If you haven't finished the game, this may contain spoilers for you!

I have a problem: I finished the game by killing Trevor.

The mission came as a surprise to me.

I couldn't save the game, when I had to make a choice on my mobile. Now the game is over and I was supposed to finish some side-missions. But Trevor is missing.

Why the hell isn't he playable, when the story is over anyway?? Is there a way to get him back, other than loading an old savepoint?

I don't understand. You killed trevor, but you are upset that you can't play as him? He's dead, what were you expecting?

Sounds like you are going to have to return to the old savepoint.

No luck there pal. You have to go back now. I saved them both and went to youtube for the other endings.