I think the song is about someone who's in coma; "well I know you lay in bed, contemplating your own death". He/she is between life and death. He/she and wasn't taking care of him/herself ( that's mostly what brought him/her into coma ) and was mutilating him/herself ( "you just wanna stab again" and "you can dig so deep for scars" ). Also, there's an artificial breathing sound at a moment. And all of this is because of depression. Now he/she's at the hospital ( "cold white walls..." ). His/her lover came to see the person to "talk" with him/her and say "breathe with me" and " don't you dare forget the sun". That means "don't lose hope".
Now they're both kind of desperate ( "dear diary, life is trying me, can I get a sign ? Or a two of mind, a piece of mind ?" ).