This entire post is a projection, especially this paragraph. Your advice is essentially telling her what to do if you were her brother. Keep your personal shit out of this.on one hand, he sounds like he is sick....he probably can't stop thinking about his self-worth, feeling guilty as hell, which drives him to torture you even more.....he doesn't give a shit about you and your child's food or household things because he doesn't give a shit about his own life...he doesn't live for anything or feels attached to anything other than his own shitty life. I don't think he is doing it to terrorize you...little bit of interactions he does get probably gives him that satisfaction...
eating, smoking, and all the "indulging" that he does is probably a sign that his brain is completely turned off to everything else...I should probably ask...does he get out often? Is he secluded?
P.S. You're a fucking asshole for calling "get out" solutions selfish. Rav is quite obviously a bleeding heart, which means any little hint of an outrageous "oh maybe try helping him?" statement is a risk of not making the obviously-correct solution (getting out) not obviously correct to her.