So, this song about, how after a breakup people may be worn down and that he is gonna need to heal from the girl because he loved her.
"You watch me bleed until I can't breathe" is symbolizing how he is so sad that he sometimes can't even breathe. I can see where you get the self harm, but Shawn wouldn't encouage that in him music.
Same thing with "I'm shaking, falling onto my knees" it's like he is hurt so much he can't even stand up. And then "and now that I'm without you kisses,
I'll be needed stitches" means that, without her love he will need "stitches" like help healing becaus he loved her so much
"Stitches"
I thought that I'd been hurt before
But no one's ever left me quite this sore
Your words cut deeper than a knife
Now I need someone to breathe me back to life
Got a feeling that I'm going under
But I know that I'll make it out alive
If I quit calling you my lover
Move on
You watch me bleed until I can't breathe
Shaking, falling onto my knees
And now that I'm without your kisses
I'll be needing stitches
Tripping over myself
Aching, begging you to come help
And now that I'm without your kisses
I'll be needing stitches
Just like a moth drawn to a flame
Oh, you lured me in, I couldn't sense the pain
Your bitter heart cold to the touch
Now I'm gonna reap what I sow
I'm left seeing red on my own
Got a feeling that I'm going under
But I know that I'll make it out alive
If I quit calling you my lover
Move on
You watch me bleed until I can't breathe
Shaking, falling onto my knees
And now that I'm without your kisses
I'll be needing stitches
Tripping over myself,
Aching, begging you to come help
And now that I'm without your kisses
I'll be needing stitches
Needle and the thread,
Gotta get you out of my head
Needle and the thread,
Gonna wind up dead
Needle and the thread,
Gotta get you out of my head, get you out of my head
You watch me bleed until I can't breathe
Shaking, falling onto my knees (falling on my knees)
And now that I'm without your kisses
I'll be needing stitches (and I'll be needing stitches)
Tripping over myself,
Aching, begging you to come help (begging, "Baby,
please.")
And now that I'm without your kisses
I'll be needing stitches