Bit of a back story. So I have this cousin, who I shall call "E" who is 21, loving guy,  big heart, is very supportive of his family, but very unreliable because of his girlfriend. His girlfriend who I'll call Emma, is an emotionally and physically abusive bitch, basically steals his money, as she refuses to work, will constantly fight with him and doesn't have the decency to do that in private. My whole problem with him is, he constantly will break up and get back the next day, or he'll ghost his entire family including me, one of the only friends he has for months, sometimes up to a year. 

Due to recent events in the family including losing my father to a heart attack, I've decided to just cut him off as I view him nothing more than a lost cause/unneeded stress at this point. I talked with my aunt about this and she was very much against it saying he's young and that eventually he'll learn from this, but in my eyes he's old enough at this point, and should've gotten his situation figured out, she's really nothing more than a parasite.  Don't get me wrong I love my cousin to death, he means the world to me, he's basically the only true friend i have in this world or so I think, but I feel like he just has his head too far up this girls ass to realize what he's doing to his family. 

TLDR: Cousin is blind with love, for a girl who abuses him and drains him of money, I want to cut him off because its caused me stress and problems for years, family thinks I'm the asshole for thinking this way.