Here is a song interpretation of 3 1/2 by AFI, I wrote for this site, http://www.songmeanings.net/lyric.php?lid=13882&flush=true

I got the feel of suicide so here is a line by line interpretation on what I think.

"Open wounds in the palms of my hands,"
I think this means like him paying for his sins/actions like in christianity Jesus got nailed through his palms. I know Davey in these albums sing about his feelings and all but that doesn't mean that he still couldn't use a bible reference to show his feelings. He did go to a catholic school as a child and this wouldn't be the first time he's used a reference.

"festering through infectious time."
He is becoming an inrritaion or poison to himself as time goes by.

"I feel so faint as my life spills over you."
He can't hold in his feelings and problems in anymore and it is "spilling" out of him and affecting the people around him and making him feel worse.

"Backstep over glass as I repent."
As he looks back at all the hard times and he feel regret and remorse for all that's happened.

"I fear I cannot prevent myself from spilling your life all over me."
He is trying to help other people and can't help himself in trying to take everyone else's problems.

"I'm so sick, so sick of myself."
Pretty literal. He is tried of himself, he can't stand who is.

"Mother, say you'll pray for me."
Again pretty literal. He wants help. I also got the impression that he wants the prayer to guide his spirit to heaven/afterlife when he kills himself.

"I'm premature in my decay."
He is "dying" slowly at a young age. This pain and slowly decay of his mental health shouldn't happen to someone so young.

"Shards of glass swimming in my eyes."
Like the people above these are his tears.

"A small voice in the back of my mind that's whispering words I never want to hear."
Everyone has a voice in the back of your head that is always talking. This is the voice that tell you that you are going to fail a test or that you should be carefull and such. It doesn't always says things you want to hear. From experience I have found that the voice can be against you and can tell you to kill yourself. I think that is what the voice is telling him but he is resisting.

"I pray that you won't hesitate as you watch me degenerate to reach in my wounds and extract all of my fear."
Now degenerate means to have fallen to undesirable state so with that I think this is a call for help. He wants the people around him to help him and take away his fear either in helping him get better or help him in finalizing his decision to kill himself.

"My suffocation, asphyxiation. I've been choking on my own blood."
His very being is killing him. He feels it's something unavoidable because he is the problem.

Those are my thoughts but AFI is mysterous and don't have specific meanings to their songs, so there you go.