Just cancel graduation?

I'm graduating in May, I was super excited when they announced an in person commencement and I could actually walk across stage! We're allowed 4 guests, and I had planned on taking my mother, my boyfriend, my dad, and my step mom. My mom absoloutly hates my step mom. And in all honestly she has no need to, that's my dads wife, they got married very recently, but they've been together for years and my parents have divorced since i was very little. Idk what the actual problem is but my step mom never pays no mind to my mom hating on her. Anyway, my mom knew i was giving a ticket to my step mom, and she was acting more mature about it at first than i had expected. Althought she did try to say i should let my grandpa go instead. (But i said no because him and my grandma are coming in from out of town and if i can't take both then i can't take either. And on top of that I'm not really close to them like that). But now today she started complaining about not wanting to "sit too close to that bitch" and she also doesnt want to bbq at my house after the ceremony and celebrate because of my step mom. I feel like she would rather we petty than just be there for me. Im the first in my family to graduate college, and im the second youngest of 5 kids. I just want it to be more important for her to be more proud of me than it is important for her to be bitter. So i just told my family I'm just cancelling all the festivities. Is that the wrong thing to do? My boyfriend says if i do that I'm just letting her win and i should just do what i had originally planned and not let her negativity ruin everything. But if she doesn't go I'll never hear the end of it and it'll forever be my fault because "im putting my step mom over her." I just idk what to do 😞 im not asking her to be beat friends with my step mom im literally just asking to be in the same vicinity and not be rude. But apparently that's too much for her and now i just don't want to do anything.

Side note: its a small party with just immediate family. My grandparents are vaccinated and our family sees each other pretty often and we're all covid safe.