You are pretty dense, aren't you? Your boy is a liar, once he got his loot and his new screwpal, he "remembered" Terri wanted to die. But you know that already.
With what to gain?
As you said, he had his loot, he had his screwpal -- her parents offered to care for her, bada bing, bada boom, he's gone.
But he didn't do that. It couldn't have been because he was after Terr's trust fund (unlike her parents) -- in 1998 he offered, in writing, to donate that to charity.
So, Mr. Non-Dense one, why did he stay? Why did he want Terri to die? You're so friggin' smart, tell me.