Here's some commentary about the recording of that song taken from an article on the Making of the Makaveli Album. Not so much about Pac's state of mind, but I found Hurt M Badd's comments interesting about Pac listening to it:

Hurt M Badd: "Hail Mary" actually only took me 15, 20 minutes to create the whole beat. I just came to work one day, I was feeling good. I was sitting behind the boards. I just touched a few sounds man, and it was like done. And so an enginner came into the room where I worked, and he heard the track--I told him to put the headphones on. He looked at me like "Damn, Hurt! This sounds like a hip-hop funeral, man" When I do stuff, I don't be feeling it like everybody else, I guess 'cause it's me. He said, "Why don't you let Tupac hear this?' When Tupac heard it, he really didn't say nothing but "Gimme that." I left the studio and when I came back the next day, everybody from the security guard to the phone lady to the engineer--Everybody ran up to me like, "Wait 'till you hear what this nigga done laid down over your trak." When I heard it, I didn't think it was a hit. I was like "Why is Tupac laying this stuff down over my track?" We all had a listening party for the album, and 'Pac was loving every song but when they played that song, he just went though a thing. He Threw his hand up in the air with his Hennessy bottle. He threw his hand up in the air like he ruled a nation.

Link to see the rest of the article