I (21F) want to break up with my boyfriend (24M) but he lives in my apartment

My boyfriend moved into my apartment on the university campus that I study at (the uni permits partners staying here) and for reasons mainly discussed in my previous post, I’ve reached the point of wanting to break up. I feel as though when I found out that he misses his ex, I emotionally checked out of the relationship straight away. It’s been a bit over a week now and he’s doing everything to compensate for it and reassure me that he wasn’t in a good mental state and that he doesn’t even miss her, but I just know that I’m going to evolve into a needy, desperate, insecure mess and second-guess everything about me from this point onwards.

The thing is, I just want to break up with him and not see him again. When we’ve previously had fights and talked about breaking up, he’s always said “give me a month to figure everything out and then I’ll move out.” I don’t want to have him in my presence for a month. I feel like it would hurt too much and I might end up caving and getting back together with him (he does not want to break up). Also there is only one bed so he’d have to sleep with me for a whole month. By the way, this is my apartment that I’ve rented for ages before I met him and I am still studying at the university so there’s no way I’m going to move out. Furthermore, when he moved in, he started paying for half of the rent so he’s not leeching off me financially like some people suggested previously.

Any advice would be greatly appreciated, I don’t know what to do.

TL;DR I found out my bf still thinks about and misses his ex, I want to break up but he is living in my apartment