Not to rub salt in the wound but previously when Stefan been struggling either with his dark side or his humanity or his life he has managed to fight for it because of Elena. Because of that one girl who made him want to live. Even when he became a ripper again and Klaus had him kill people, he kept his humanity on regardless of the grief and self hatred that came with it because he didn’t want to lose the way he felt about her. He had someone to go back to, something to fight for.
“Through all of this, you are the one thing that has kept me from giving up, from turning it all off” / “I found something else to live for” and now he has nothing. He will be drowning and dying over and over again, without a shred of hope, without anything to go back to/fight for and that breaks my heart.