boyfriend issues

My boyfriend really want to have a threesome like he keeps asking me and yes shitty when I say I don't want to cause I'm not into that type of stuff like it just seems wrong to me like I don't want to see him fucking another girl like I just wouldn't be able to see that and he is like it would only be a one night thing but like I don't want to it's just not right to me. It's to the point where he is like u can say bye to me cause I'm gonna go do so and so cause I'm saying no to the threesome like i don't know why he is getting so mad about it !!!