失えば己の存在自体も揺らぐほどの... 大切な何かがある... とか
Actually, it's helpful to read it backward: Like... there's something so important... that if you lose it, your very existence will be shaken
I'm seriously surprised, you teenage bastard. I think (not 100% sure) that 厨二 stands for 2nd grade in middle school (see 厨二病), a term used to refer to poor teenagers suffering through puberty.
Thanks for this, I had the top one down as something along the lines of:
"If you lose something so important like your self-being, your very existence would be shaken...right?"
(the とか had a ? afterwards)
Thanks for the 厨二 help, it was the part that threw me off slightly.