Is it bad to hate my boyfriend for getting a cat I’m allergic to and disrespecting me?

I (23F) have been with my boyfriend (25M) on and off for three years. When we first started dating, his cat lived with his family, so I didn’t have to deal with it. For context, I’m allergic to cats, and this particular cat is very aggressive—it was originally a feral barn cat that his family took in. Since my boyfriend moved into a studio apartment, he brought the cat with him, and it’s been a problem.

When we originally broke up, it was because I tried to do the right thing with my own dog. I had adopted a reactive rescue dog, but she struggled badly in the city. She was so scared she wouldn’t even pee at night, to the point of developing UTIs. I felt irresponsible keeping her in that environment. I tried to have her live with my mom in the country, but she didn’t get along with my mom’s dog. I lost my housing soon after and couldn’t keep her. It was devastating, but I rehomed her in a good situation where she now goes to work every day with her owner in a rural area, which fits her as a working line shepherd. My boyfriend didn’t support my decision, and that’s when he broke up with me.

Now, since we got back together, he’s living with his cat in his new place. The cat attacks me whenever I sit next to him on the couch or even if I move in bed at night. If the cat gets annoyed, my boyfriend gets angry at me instead of addressing the cat’s behavior. He even cussed me out recently because I moved in bed and the cat lashed out at me.

I feel a lot of resentment, because I had to give up my dog—something I still grieve—while he insists on keeping this aggressive cat that actively makes my life miserable. I honestly don’t know what to do at this point and need advice.

TL;DR: I (23F) had to rehome my rescue dog in a heartbreaking decision, and my boyfriend (25M) broke up with me at the time over it. Now that we’re back together, his aggressive cat attacks me constantly, but he blames me instead of the cat. I resent him for this and for the fact I lost my dog while he insists on keeping his cat. What do I do?