Wht Does This Song Make Me Cry Really Hard? (read descrition)?

Well the song I Miss You by Blink182 makes me cry so hard that i cant
stop, people are telling me im depressed (my friends), but i just dont
know anymore. I cut at times but i stopped, because i was judged. i
had a TERRIBLE past. But im not allowed to tell the story. I really
miss my grandma that i cant see for reasons. Why does it make me cry
this hard. Please help