Easter drama

So my boyfriend shares custody of his 5 y/o with the maternal grandparents. Mom is an addict and pops in and out as she pleases when they actually allow. My boyfriend works out of town for a month and is home for 2 weeks. We bought a home in his school’s jurisdiction and everything bc we have little man the entire 2 weeks. Well Easter is this weekend, grandma let me know 2 weeks ago about their small Easter get together, I obviously agreed to go bc I miss the kid like crazy when he’s gone. Fast forward to today well yesterday really, anyways bio mom calls and says she wants to see her son on Easter. Grandma told her that was fine but she had to 1st past a drug test in order to see him and 2nd she had to promise there would be no drama with me there bc little man specifically asked if I could come. Mind you, she hasn’t laid eyes on her child since HALLOWEEN. No calls, nothing. Of course bio mom flies off the fucking handle and says if I’m there she won’t be. Now I’m conflicted because I don’t want him to miss out on a once in a blue moon visit with his mom but I also don’t want to disappoint him in my not showing up bc he’s been made aware that I will be there 😐

Update*** I called my boyfriend today (he’s at work and will be home next week) and spoke to him about it. He for lack of a better word said that she can kiss his ass. I called grandma who then told me “if she has that big of an issue than she needs not to come because you play a role in his life that she doesn’t. You’re his constant not her” so we shall see how Sunday turns out 😅 I would NEVER feed into her in front of the kiddo. She knows that as she’s tried to bust my car window out before with him in my back seat bc she seen us at Walmart 🙂 but I can’t say that I wouldn’t scrub her if she tried me when I wasn’t in the presence of her son. 😅