Don’t want to invite my future Bil’s girlfriend

My future BIL’s girlfriend is an awful person and makes it very obvious she does not like me & in simple terms, I do not like her back. They have been together 5+ years, on the road to engagement, do not live together, however she is in fact “apart of the family”. She has done very horrible things to me down to not even saying I’m sorry (or acknowledging it even once) when my mom passed away. Never said congratulations to me when I got engaged. Started a “family” group chat and excluded me. The list goes on but for just the first reason alone I am hurt. My fiancé’s is EXTREMELY small so as of now, she is one of the core members. We are having a small intimate wedding because all we want is the people who love & support us with us on our special day & she DOES NOT. I don’t know what to do because we are inviting people who have been in long term relationships (even if not married) with their +1’s so it’s not like we can use that excuse. I also don’t want my BIL to threaten him not going if she is not invited because like I said, they’re family is so small and I’d hate to be the reason for my fiancés brother to not be at the wedding but the mere thought of her being there on the most special day of my life makes me so angry. My fiancé is supportive in whatever decision I make. I’d love any and all advice/if anyone has gone through a similar situation. Thanks in