boyfriend has ton of nude hentai all over apartment

I'm posting this on another sub-reddit for more advice.

I've been with my boyfriend for 4 years.

Within the past month he keeps buying stickers and posters of naked anime / hentai and putting it everywhere in the apartment. I'm really not comfortable with this, and it bothers me even more because I sometimes have to pick up my nephew that is 10 from school and I watch him at the apartment until someone picks him up to go home. My mom also comes to visit so I try to hide the stuff but there is so much it's really difficult. He also has some in his car and it's noticeable to passengers, for example his best friend saw it and said, " why tf do you have naked pictures of women in your car dude? Your gf is right here." And my boyfriend just laughed and didn't say anything. The picture I'm referencing for that situation is a real person btw, idk who the model is or anything.

He also has a huge poster (made out of cloth, I know there is another name for this but I can't remember), of a naked anime girl fingering herself. ( it covers the entire wall, like 6 feet tall)

I don't even know what to do anymore. I told him I didn't like it and that I felt disrespected, but he just says, " I can't have anything nice." His friends have even asked me privately on the side why is he doing this and they feel bad for me.

Ever since he got his job as a correctional officer last year he completely changed. I don't know what to do.