Boyfriend suddenly turns into monster during my moms death?

Do any of you have experiences with partners during the passing of your parents? Im 26 and only one year and a half into my relationship, my mom is currently dying (only family I have) and my bf became so distant and cold to me. Zero empathy, and in fights really mean and unapologetic ( he basically ignores me and sleeps on the couch since yesterday). I don’t understand his behaviour I would neverrr act like that if he were in my situation? Are people really this bad, does that mean I should break up and be completely alone during my moms passing? He also said things like “better be really nice to me now I soon will be the only thing that you have” during a fight a couple days ago, that still shocks me to this day. Is my boyfriend really this monster and I never noticed the whole time or is this a sort of stress reaction to a young grieving partner??